Null Data Packet (NDP) Ranging Measurement Feedback

ABSTRACT

A first communication device determines which one or more types of feedback information, from among a plurality of types of feedback information associated with a range measurement exchange session, a second communication device is to provide to the first communication device in a feedback packet transmitted as part of the range measurement exchange session. The first communication device transmits to the second communication device one or more indications of the determined one or more types of feedback information that the second communication device is to provide to the first communication device in the feedback packet. The first communication device performs the range measurement exchange, including receiving the feedback packet from the second communication device, wherein the feedback packet includes the determined one or more types of feedback information.

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/489,822, entitled “Null Data Packet (NDP) RangingMeasurement Feedback,” filed on Apr. 25, 2017, and U.S. ProvisionalPatent Application No. 62/536,366, entitled “Null Data Packet (NDP)Ranging Measurement Feedback,” filed on Jul. 24, 2017. The disclosuresof both of the applications referenced above are expressly incorporatedherein by reference in their entireties.

FIELD OF TECHNOLOGY

The present disclosure relates generally to wireless communicationsystems, and more particularly to communication exchanges betweenwireless communication devices for measuring distances among thewireless communication devices.

BACKGROUND

Wireless local area networks (WLANs) have evolved rapidly over the pastdecade, and development of WLAN standards such as the Institute forElectrical and Electronics Engineers (IEEE) 802.11 Standard family hasimproved single-user peak data throughput. For example, the IEEE 802.11bStandard specifies a single-user peak throughput of 11 megabits persecond (Mbps), the IEEE 802.11a and 802.11g Standards specify asingle-user peak throughput of 54 Mbps, the IEEE 802.11n Standardspecifies a single-user peak throughput of 600 Mbps, and the IEEE802.11ac Standard specifies a single-user peak throughput in thegigabits per second (Gbps) range. Future standards promise to provideeven greater throughput, such as throughputs in the tens of Gbps range.

Some mobile communication devices include a WLAN network interface andsatellite positioning technology, such as global positioning system(GPS) technology. GPS technology in mobile communication devices isuseful for navigating to a desired location, for example. However, GPStechnology does not typically provide accurate location information whena GPS receiver is not in direct sight of a GPS satellite, and thus GPStechnology is often not useful for providing location information whilea mobile communication device is within a building such as an airport, ashopping mall, etc., within a tunnel, etc.

Techniques for determining a position of a communication device usingWLAN technology are now under development. For example, a distancebetween a first communication and a second communication device isdetermined by measuring a time of flight of WLAN transmissions betweenthe first communication device and the second communication device, andthe determined distance. Similarly, distances between the firstcommunication device and multiple third communication devices aredetermined. Then, the determined distances are used to estimate alocation of the first communication device by employing, for example, atriangulation technique. For a first communication device havingmultiple antennas, an angle of departure (AoD) of a WLAN transmissioncan be determined. Similarly, for a second communication device havingmultiple antennas, an angle of arrival (AoA) of the WLAN transmissionfrom the first communication device can be determined. The AoD and theAoA, along with the determined distances, can be also be used forestimating the location of the first communication device.

SUMMARY

In an embodiment, a method includes: determining, at a firstcommunication device, which one or more types of feedback information,from among a plurality of types of feedback information associated witha range measurement exchange session, a second communication device isto provide to the first communication device in a feedback packettransmitted as part of the range measurement exchange session;transmitting, by the first communication device and to the secondcommunication device, one or more indications of the determined one ormore types of feedback information that the second communication deviceis to provide to the first communication device in the feedback packet;and performing, at the first communication device, the range measurementexchange, including receiving the feedback packet from the secondcommunication device, wherein the feedback packet includes thedetermined one or more types of feedback information.

In another embodiment, an apparatus comprises: a network interfacedevice associated with a first communication device. The networkinterface device includes: one or more integrated circuits (ICs), amedia access control layer protocol (MAC) processor implemented on theone or more ICs, and a physical layer protocol (PHY) processorimplemented on the one or more ICs. The MAC processor is configured to:determine which one or more types of feedback information, from among aplurality of types of feedback information associated with a rangemeasurement exchange session, a second communication device is toprovide to the first communication device in a feedback packettransmitted as part of the range measurement exchange session. Thenetwork interface device is configured to: transmit, to the secondcommunication device, one or more indications of the determined one ormore types of feedback information that the second communication deviceis to provide to the first communication device in the feedback packet,and perform the range measurement exchange, including receiving thefeedback packet from the second communication device, wherein thefeedback packet includes the determined one or more types of feedbackinformation.

In yet another embodiment, a method includes: determining, at a firstcommunication device, which one or more types of feedback information,from among a plurality of types of feedback information associated witha range measurement exchange session, the first communication device isto provide to a second communication device in a feedback packettransmitted as part of the range measurement exchange session; andperforming, at the first communication device, the range measurementexchange with the second communication device, including transmittingthe feedback packet to the second communication device, wherein thefeedback packet includes the determined one or more types of feedbackinformation.

In still another embodiment, an apparatus comprises: a network interfacedevice associated with a first communication device. The networkinterface device includes: one or more integrated circuits (ICs), amedia access control layer protocol (MAC) processor implemented on theone or more ICs, and a physical layer protocol (PHY) processorimplemented on the one or more ICs. The MAC processor is configured to:determine which one or more types of feedback information, from among aplurality of types of feedback information associated with a rangemeasurement exchange session, is to be provided to a secondcommunication device in a feedback packet transmitted as part of therange measurement exchange session. The network interface device isconfigured to: perform the range measurement exchange, includingtransmitting the feedback packet to the second communication device,wherein the feedback packet includes the determined one or more types offeedback information.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example wireless local area network(WLAN), according to an embodiment.

FIG. 2A is a diagram of an example multi-user (MU) ranging measurementexchange in an MU ranging measurement procedure, according to anembodiment.

FIG. 2B is a timing diagram of the example MU ranging measurementexchange of FIG. 2A, according to an embodiment.

FIG. 2C is a diagram of another MU ranging measurement exchange in an MUranging measurement procedure, according to another embodiment.

FIG. 2D is a timing diagram of the example MU ranging measurementexchange of FIG. 2C, according to an embodiment.

FIG. 2E is a diagram of another MU ranging measurement exchange in an MUranging measurement procedure, according to an embodiment.

FIG. 3 is a diagram of another MU ranging measurement exchange in an MUranging measurement procedure, according to another embodiment.

FIG. 4 is a flow diagram of an example method for performing an MU rangemeasurement exchange, according to an embodiment.

FIG. 5 is a flow diagram of another example method for performing an MUrange measurement exchange, according to another embodiment.

FIG. 6 is a diagram of another MU ranging measurement exchange in an MUranging measurement procedure, according to another embodiment.

FIG. 7 is a diagram of another MU ranging measurement exchange in an MUranging measurement procedure, according to another embodiment.

FIG. 8 is a diagram of another MU ranging measurement exchange in an MUranging measurement procedure, according to another embodiment.

FIG. 9 is a diagram of another MU ranging measurement exchange in an MUranging measurement procedure, according to another embodiment.

FIG. 10 is a flow diagram of an example method for initiating atransmission of feedback in an MU range measurement exchange, accordingto an embodiment.

FIG. 11A is a diagram of an example single-user (SU) ranging measurementexchange in an SU ranging measurement procedure, according to anembodiment.

FIG. 11B is a timing diagram of the example SU ranging measurementexchange of FIG. 11A, according to an embodiment.

FIG. 12 is a diagram of another SU ranging measurement exchange in an SUranging measurement procedure, according to another embodiment.

FIG. 13 is a diagram of another SU ranging measurement exchange in an SUranging measurement procedure, according to another embodiment.

FIG. 14 is a diagram of another SU ranging measurement exchange in an SUranging measurement procedure, according to another embodiment.

FIG. 15 is a flow diagram of an example method for performing an SUrange measurement exchange, according to an embodiment.

FIG. 16 is a flow diagram of another example method for performing an SUrange measurement exchange, according to another embodiment.

FIG. 17 is a flow diagram of an example method for initiating atransmission of feedback in an SU range measurement exchange, accordingto an embodiment.

DETAILED DESCRIPTION

Ranging measurement techniques described below are discussed in thecontext of wireless local area networks (WLANs) that utilize protocolsthe same as or similar to protocols defined by the 802.11 Standard fromthe Institute of Electrical and Electronics Engineers (IEEE) merely forexplanatory purposes. In other embodiments, however, ranging measurementtechniques are utilized in other types of wireless communication systemssuch as personal area networks (PANs), mobile communication networkssuch as cellular networks, metropolitan area networks (MANs), etc.

FIG. 1 is a block diagram of an example WLAN 110, according to anembodiment. The WLAN 110 includes an access point (AP) 114 thatcomprises a host processor 118 coupled to a network interface device122. The network interface 122 includes a medium access control (MAC)processor 126 and a physical layer (PHY) processor 130. The PHYprocessor 130 includes a plurality of transceivers 134, and thetransceivers 134 are coupled to a plurality of antennas 138. Althoughthree transceivers 134 and three antennas 138 are illustrated in FIG. 1,the AP 114 includes other suitable numbers (e.g., 1, 2, 4, 5, etc.) oftransceivers 134 and antennas 138 in other embodiments. In someembodiments, the AP 114 includes a higher number of antennas 138 thantransceivers 134, and antenna switching techniques are utilized.

The network interface 122 is implemented using one or more integratecircuits (ICs) configured to operate as discussed below. For example,the MAC processor 126 may be implemented, at least partially, on a firstIC, and the PHY processor 130 may be implemented, at least partially, ona second IC. As another example, at least a portion of the MAC processor126 and at least a portion of the PHY processor 130 may be implementedon a single IC. For instance, the network interface 122 may beimplemented using a system on a chip (SoC), where the SoC includes atleast a portion of the MAC processor 126 and at least a portion of thePHY processor 130.

In an embodiment, the host processor 118 includes a processor configuredto execute machine readable instructions stored in a memory device (notshown) such as a random access memory (RAM), a read-only memory (ROM), aflash memory, etc. In an embodiment, the host processor 118 may beimplemented, at least partially, on a first IC, and the network device122 may be implemented, at least partially, on a second IC. As anotherexample, the host processor 118 and at least a portion of the networkinterface 122 may be implemented on a single IC.

In various embodiments, the MAC processor 126 and/or the PHY processor130 of the AP 114 are configured to generate data units, and processreceived data units, that conform to a WLAN communication protocol suchas a communication protocol conforming to the IEEE 802.11 Standard oranother suitable wireless communication protocol. For example, the MACprocessor 126 may be configured to implement MAC layer functions,including MAC layer functions of the WLAN communication protocol, andthe PHY processor 130 may be configured to implement PHY functions,including PHY functions of the WLAN communication protocol. Forinstance, the MAC processor 126 may be configured to generate MAC layerdata units such as MAC service data units (MSDUs), MAC protocol dataunits (MPDUs), etc., and provide the MAC layer data units to the PHYprocessor 130. The PHY processor 130 may be configured to receive MAClayer data units from the MAC processor 126 and encapsulate the MAClayer data units to generate PHY data units such as PHY protocol dataunits (PPDUs) for transmission via the antennas 138. Similarly, the PHYprocessor 130 may be configured to receive PHY data units that werereceived via the antennas 138, and extract MAC layer data unitsencapsulated within the PHY data units. The PHY processor 130 mayprovide the extracted MAC layer data units to the MAC processor 126,which processes the MAC layer data units.

The PHY processor 130 is configured to downconvert one or more radiofrequency (RF) signals received via the one or more antennas 138 to oneor more baseband analog signals, and convert the analog basebandsignal(s) to one or more digital baseband signals, according to anembodiment. The PHY processor 130 is further configured to process theone or more digital baseband signals to demodulate the one or moredigital baseband signals and to generate a PPDU. The PHY processor 130includes amplifiers (e.g., a low noise amplifier (LNA), a poweramplifier, etc.), a radio frequency (RF) downconverter, an RFupconverter, a plurality of filters, one or more analog-to-digitalconverters (ADCs), one or more digital-to-analog converters (DACs), oneor more discrete Fourier transform (DFT) calculators (e.g., a fastFourier transform (FFT) calculator), one or more inverse discreteFourier transform (IDFT) calculators (e.g., an inverse fast Fouriertransform (IFFT) calculator), one or more modulators, one or moredemodulators, etc.

The PHY processor 130 is configured to generate one or more RF signalsthat are provided to the one or more antennas 138. The PHY processor 130is also configured to receive one or more RF signals from the one ormore antennas 138.

The MAC processor 126 is configured to control the PHY processor 130 togenerate one or more RF signals by, for example, providing one or moreMAC layer data units (e.g., MPDUs) to the PHY processor 130, andoptionally providing one or more control signals to the PHY processor130, according to some embodiments. In an embodiment, the MAC processor126 includes a processor configured to execute machine readableinstructions stored in a memory device (not shown) such as a RAM, a readROM, a flash memory, etc. In an embodiment, the MAC processor 126includes a hardware state machine.

The WLAN 110 includes a plurality of client stations 154. Although threeclient stations 154 are illustrated in FIG. 1, the WLAN 110 includesother suitable numbers (e.g., 1, 2, 4, 5, 6, etc.) of client stations154 in various embodiments. The client station 154-1 includes a hostprocessor 158 coupled to a network interface device 162. The networkinterface 162 includes a MAC processor 166 and a PHY processor 170. ThePHY processor 170 includes a plurality of transceivers 174, and thetransceivers 174 are coupled to a plurality of antennas 178. Althoughthree transceivers 174 and three antennas 178 are illustrated in FIG. 1,the client station 154-1 includes other suitable numbers (e.g., 1, 2, 4,5, etc.) of transceivers 174 and antennas 178 in other embodiments. Insome embodiments, the client station 154-1 includes a higher number ofantennas 178 than transceivers 174, and antenna switching techniques areutilized.

The network interface 162 is implemented using one or more ICsconfigured to operate as discussed below. For example, the MAC processor166 may be implemented on at least a first IC, and the PHY processor 170may be implemented on at least a second IC. As another example, at leasta portion of the MAC processor 166 and at least a portion of the PHYprocessor 170 may be implemented on a single IC. For instance, thenetwork interface 162 may be implemented using an SoC, where the SoCincludes at least a portion of the MAC processor 166 and at least aportion of the PHY processor 170.

In an embodiment, the host processor 158 includes a processor configuredto execute machine readable instructions stored in a memory device (notshown) such as a RAM, a ROM, a flash memory, etc. In an embodiment, thehost processor 158 may be implemented, at least partially, on a firstIC, and the network device 162 may be implemented, at least partially,on a second IC. As another example, the host processor 158 and at leasta portion of the network interface 162 may be implemented on a singleIC.

In various embodiments, the MAC processor 166 and the PHY processor 170of the client device 154-1 are configured to generate data units, andprocess received data units, that conform to the WLAN communicationprotocol or another suitable communication protocol. For example, theMAC processor 166 may be configured to implement MAC layer functions,including MAC layer functions of the WLAN communication protocol, andthe PHY processor 170 may be configured to implement PHY functions,including PHY functions of the WLAN communication protocol. The MACprocessor 166 may be configured to generate MAC layer data units such asMSDUs, MPDUs, etc., and provide the MAC layer data units to the PHYprocessor 170. The PHY processor 170 may be configured to receive MAClayer data units from the MAC processor 166 and encapsulate the MAClayer data units to generate PHY data units such as PPDUs fortransmission via the antennas 178. Similarly, the PHY processor 170 maybe configured to receive PHY data units that were received via theantennas 178, and extract MAC layer data units encapsulated within thePHY data units. The PHY processor 170 may provide the extracted MAClayer data units to the MAC processor 166, which processes the MAC layerdata units.

The PHY processor 170 is configured to downconvert one or more RFsignals received via the one or more antennas 178 to one or morebaseband analog signals, and convert the analog baseband signal(s) toone or more digital baseband signals, according to an embodiment. ThePHY processor 170 is further configured to process the one or moredigital baseband signals to demodulate the one or more digital basebandsignals and to generate a PPDU. The PHY processor 170 includesamplifiers (e.g., an LNA, a power amplifier, etc.), an RF downconverter,an RF upconverter, a plurality of filters, one or more ADCs, one or moreDACs, one or more DFT calculators (e.g., an FFT calculator), one or moreIDFT calculators (e.g., an IFFT calculator), one or more modulators, oneor more demodulators, etc.

The PHY processor 170 is configured to generate one or more RF signalsthat are provided to the one or more antennas 178. The PHY processor 170is also configured to receive one or more RF signals from the one ormore antennas 178.

The MAC processor 166 is configured to control the PHY processor 170 togenerate one or more RF signals by, for example, providing one or moreMAC layer data units (e.g., MPDUs) to the PHY processor 170, andoptionally providing one or more control signals to the PHY processor170, according to some embodiments. In an embodiment, the MAC processor166 includes a processor configured to execute machine readableinstructions stored in a memory device (not shown) such as a RAM, a ROM,a flash memory, etc. In an embodiment, the MAC processor 166 includes ahardware state machine.

In an embodiment, each of the client stations 154-2 and 154-3 has astructure that is the same as or similar to the client station 154-1.Each of the client stations 154-2 and 154-3 has the same or a differentnumber of transceivers and antennas. For example, the client station154-2 and/or the client station 154-3 each have only two transceiversand two antennas (not shown), according to an embodiment.

PPDUs are sometimes referred to herein as packets. MPDUs are sometimesreferred to herein as frames.

FIG. 2A is a diagram of an example multi-user (MU) ranging measurementexchange 200 in an MU ranging measurement procedure, according to anembodiment. The diagram 200 is described in the context of the examplenetwork 110 merely for explanatory purposes. In some embodiments,signals illustrated in FIG. 2A are generated by other suitablecommunication devices in other suitable types of wireless networks.

The MU ranging measurement exchange 200 corresponds to an AP-initiatedMU ranging measurement exchange, according to an embodiment. The MUranging measurement exchange 200 includes an uplink (UL) null datapacket (NDP) frame exchange 204, a downlink (DL) NDP transmissionportion 208, and an UL feedback frame exchange 212. In an embodiment,the uplink UL NDP frame exchange 204, the DL NDP transmission portion208, and the UL feedback frame exchange 212 occur within a singletransmit opportunity period (TXOP). In another embodiment, the uplink ULNDP frame exchange 204, the DL NDP transmission portion 208, and the ULfeedback frame exchange 212 do not occur within a single TXOP.

In the UL NDP exchange 204, a first communication device (e.g., the AP114) transmits a DL PPDU 216 that includes a trigger frame to cause agroup of multiple second communication devices (e.g., client stations154) to simultaneously transmit, as part of an uplink (UL) MUtransmission 220, UL null data packets (NDPs) 224. In an embodiment, thetrigger frame in the PPDU 216 is a type of trigger frame specificallyfor initiating an MU ranging measurement exchange such as the MU rangingmeasurement exchange 200. The trigger frame in the PPDU 216 causesmultiple client stations 154 to begin simultaneously transmitting the ULMU transmission 220 a defined time period after an end of the PPDU 216216. In an embodiment, the defined time period is a short interframespace (SIFS) as defined by the IEEE 802.11 Standard. In otherembodiments, another suitable time period is utilized.

In an embodiment, the UL MU transmission 220 includes an UL MU multipleinput, multiple output (MIMO) transmission having two or more UL NDPs224 from multiple client stations 154, e.g., STA1, STA2, STA3, and STA4.The two or more of the UL NDPs 224 are transmitted within a samefrequency band via different spatial streams (e.g., MU-MIMO). In anotherembodiment, the UL MU transmission 220 includes an UL orthogonalfrequency division multiple access (OFDMA) transmission having two ormore UL NDPs 224 from multiple client stations 154, e.g., STA1, STA2,STA3, and STA4, in different respective frequency bandwidth portions. Inyet another embodiment, three or more UL NDP packets 224 transmittedusing a combination of UL MU-MIMO and UL OFDMA, where at least two NDPsare transmitted using MU-MIMO in a same frequency bandwidth portion viadifferent spatial streams, and at least one NDP is transmitted in atleast one other different frequency bandwidth portion. The UL NDPs 224include PHY preambles having one or more short training fields (STFs),one or more long training fields (LTFs) and one or more signal fields,in an embodiment. The UL NDPs 224 omit data portions.

When transmitting the UL NDPs 224, each client station 154 records atime t_(1,k) at which the client station 154 began transmitting the ULNDP 224, where k is an index indicating the particular client station154. Similarly, when the AP 114 receives each UL NDP 224, the AP 114records a time t_(2,k) at which the AP 114 began receiving the UL NDP224.

In some embodiments, when transmitting the UL NDPs 224, each of at leastsome of the client stations 154 (e.g., client stations 154 with multipleantennas 174) records an angle of departure, AoD_(1,k), at which the ULNDP 224 left the antennas 178 of the client station 154. Similarly, whenthe AP 114 receives each UL NDP 224, the AP 114 records an angle ofarrival, AoA_(1,k), at which the UL NDP 224 arrived at the antennas 138of the AP 114.

FIG. 2B is a timing diagram of the example MU ranging measurementexchange 200 of FIG. 2A. As illustrated in FIG. 2B, each client station154 records the time t_(1,k) at which the client station 154 begantransmitting the UL NDP 224, and records the AoD_(1,k) at which the ULNDP 224 left the antennas 178 of the client station 154. Additionally,the AP 114 records the time t_(2,k) at which the AP 114 began receivingeach UL NDP 224, and the AoA_(1,k), at which each UL NDP 224 arrived atthe antennas 138 of the AP 114.

Referring now to FIGS. 2A and 2B, responsive to the UL MU transmission220, the AP 114 begins transmitting a DL PPDU 228 that includes an NDPannouncement (NDPA) frame a defined time period after an end of the ULMU transmission 220. In an embodiment, the defined time period is SIFS.In other embodiments, another suitable time period is utilized. The NDPAframe in the PPDU 228 is configured to cause the client stations 154 tobe prepared to receive an NDP from the AP 114, according to anembodiment.

The AP 114 generates a DL PPDU 232 and begins transmitting the DL PPDU232 a defined time period after an end of the DL PPDU 228. In anembodiment, the defined time period is SIFS. In other embodiments,another suitable time period is utilized. The DL PPDU 232 is a MU PPDUthat includes DL NDPs 236 to respective client stations 154. In anotherembodiment, the AP 114 transmits a single DL NDP 236 using a SU DLtransmission (with a broadcast address) to the client stations 154. TheDL NDPs 236 include PHY preambles having one or more STFs, one or moreLTFs and one or more signal fields, in an embodiment. The DL NDPs 236omit data portions. The DL NDPs 236 are illustrated in FIG. 2A as beingtransmitted in different frequency bandwidth portions (e.g., OFDMA). Insome embodiments, two or more of the DL NDPs 236 are transmitted withina same frequency band (e.g., two or more of the DL NDPs 236 span thesame frequency band) using different spatial streams (e.g., the two ormore DL NDPs 236 are transmitted using MU-MIMO).

When transmitting the DL NDPs 236, the AP 114 records a time t_(3,k) atwhich the AP 114 began transmitting the DL NDP 236. Similarly, when eachclient station 154 receives the corresponding DL NDP 236, the clientstation 154 records a time t_(4,k) at which the client station 154 beganreceiving the DL NDP 236. As illustrated in FIG. 2B, the AP 114 recordsthe time t_(3,k) at which the AP 114 began transmitting the DL NDP 236,and the client station 154 records the time t_(4,k) at which the clientstation 154 began receiving the DL NDP 236.

In some embodiments, when transmitting the DL NDP 236, the AP 114records an AoD_(2,k) at which the DL NDP 236 left the antennas 138 ofthe AP 114. Similarly, when the client station 154 receives the DL NDP236, the client station 154 records an AoA_(2,k) at which the DL NDP 236arrived at the antennas 178 of the client station 154.

In some embodiments, the MU ranging measurement exchange 200 omits theDL PPDU 228. For example, the AP 114 begins transmitting the DL PPDU 232a defined time period after an end of the UL MU transmission 220. In anembodiment, the defined time period is SIFS. In other embodiments,another suitable time period is utilized.

In an embodiment, the AP 114 transmits a DL PPDU 240 a defined timeperiod after an end of the DL PPDU 232. In an embodiment, the definedtime period is SIFS. In other embodiments, another suitable time periodis utilized. The PPDU 240 includes a trigger frame to cause the group ofclient stations 154 to simultaneously transmit, as part of an UL MUtransmission 244, uplink PPDUs 248 that include ranging measurementfeedback. The trigger frame in the PPDU 240 causes multiple clientstations 154 to begin simultaneously transmitting the UL MU transmission244 a defined time period after an end of the PPDU 240. In anembodiment, the defined time period is SIFS. In other embodiments,another suitable time period is utilized.

The UL MU transmission 244 (which may be an UL OFDMA transmission or anUL MU-MIMO transmission) includes UL PPDUs 248 from multiple clientstations 154, e.g., STA1, STA2, STA3, and STA4. The UL PPDUs 248 areillustrated in FIG. 2A as being transmitted in different frequencybandwidth portions. In some embodiments, two or more of the UL PPDUs 248are transmitted within a same frequency band (e.g., two or more of theUL PPDUs 248 span the same frequency band) using different spatialstreams (e.g., the two or more UL PPDUs 248 are transmitted usingMU-MIMO).

The UL PPDUs 248 correspond to uplink ranging measurement feedbackpackets. The PPDUs 248 respectively include the recorded times t_(1,k)and t_(4,k). In some embodiments, each of one or more PPDUs 248respectively includes the recorded angles AoD_(1,k) and AoA_(2,k). Insome embodiments, the PPDUs 248 optionally also include respectivechannel estimate information determined by the client station 154 basedon reception of the DL NDPs 236.

After receipt of the PPDUs 248, the AP 114 calculates respective oftimes-of-flight between the AP 114 and the client stations 154 using therecorded times t_(1,k), t_(2,k), t_(3,k), and t_(4,k), according to anembodiment. Any suitable technique, including currently knowntechniques, may be utilized to calculate a time-of-flight using therecorded times t_(1,k), t_(2,k), t_(3,k), and t_(4,k). Respectivedistances between the AP 114 and the client stations 154 may becalculated using the calculated times-of-flight, e.g., by respectivelymultiplying the times-of-flight by the speed of light, according to anembodiment.

In some embodiments, the AP 114 calculates estimated positions of one ormore of the client stations using the calculated times-of-flight. Forexample, the AP 114 uses triangulation techniques to calculate estimatedpositions of one or more of the client stations using the calculatedtimes-of-flight. In some embodiments, the AP 114 calculates estimatedpositions of one or more of the client stations also using the recordedangles AoD_(1,k), AoA_(1,k), AoD_(2,k), and AoA_(2,k). For example, therecorded angles AoD_(1,k), AoA_(1,k), AoD_(2,k), and AoA_(2,k) are usedas part of a triangulation algorithm for determining positions ofcommunication devices.

Responsive to receipt of the PPDUs 248, the AP 114 generates a DL PPDU252 that includes one or more acknowledgment (ACK) frames 256, accordingto an embodiment. In an embodiment, the DL PPDU 252 is an MUtransmission (e.g., OFDMA and/or MU MIMO) with respective ACK frames 256for respective STAs. In another embodiment, the DL PPDU 252 includes asingle ACK frame 256 that acknowledges receipt of multiple PPDUs 248from multiple STAs. The AP 114 transmits the DL PPDU 252 a defined timeperiod after an end of the UL transmission 244. In an embodiment, thedefined time period is SIFS. In other embodiments, another suitable timeperiod is utilized.

As will be described in more detail below, the AP 114 does not generateand transmit the DL PPDU 252 even when the AP 114 successfully receivesthe UL PPDUs 248, according to an embodiment. Thus, in some embodiments,the DL PPDU 252 is omitted from the procedure 200.

FIG. 2C is a diagram of another example MU ranging measurement exchange270 in another MU ranging measurement procedure, according to anembodiment. The diagram 270 is described in the context of the examplenetwork 110 merely for explanatory purposes. In some embodiments,signals illustrated in FIG. 2C are generated by other suitablecommunication devices in other suitable types of wireless networks.

The MU ranging measurement exchange 270 corresponds to an AP-initiatedMU ranging measurement exchange, according to an embodiment. The MUranging measurement exchange 270 is similar to the MU rangingmeasurement exchange 200 of FIG. 2A, but the UL FB exchange 212 of FIG.2A is replaced with a DL FB exchange 274. In an embodiment, the uplinkUL NDP frame exchange 204, the DL NDP transmission portion 208, and theDL FB exchange 274 occur within a single TXOP. In another embodiment,the uplink UL NDP frame exchange 204, the DL NDP transmission portion208, and the DL FB exchange 274 do not occur within a single TXOP.

The DL FB exchange 274 includes a DL PPDU 278 (which may be a DL OFDMAtransmission or a DL MU-MIMO transmission) having FB frames 282 formultiple client stations 154, e.g., STA1, STA2, STA3, and STA4. The FBframes 282 are illustrated in FIG. 2C as being transmitted in differentfrequency bandwidth portions. In some embodiments, two or more of the FBframes 282 are transmitted within a same frequency band (e.g., two ormore of the FB frames 282 span the same frequency band) using differentspatial streams (e.g., the two or more FB frames 282 are transmittedusing MU-MIMO).

The FB frames 282 respectively include the recorded times t_(2,k) andt_(3,k). In some embodiments, each of one or more FB frames 282respectively includes the recorded angles AoA_(1,k) and AoD_(2,k). Insome embodiments, the FB frames 282 optionally also include respectivechannel estimate information determined by the AP 114 based on receptionof the UL NDPs 224.

After receipt of the FB frames 282, one or more of the client stations154 respectively calculate one or more respective of times-of-flightbetween the AP 114 and the one or more client stations 154 using therecorded times t_(1,k), t_(2,k), t_(3,k), and t_(4,k), according to anembodiment. Any suitable technique, including currently knowntechniques, may be utilized to calculate a time-of-flight using therecorded times t_(1,k), t_(2,k), t_(3,k), and t_(4,k). Respectivedistances between the AP 114 and the client stations 154 may becalculated using the calculated times-of-flight, e.g., by respectivelymultiplying the times-of-flight by the speed of light, according to anembodiment.

In some embodiments, one or more of the client stations 154 calculatesestimated positions of one or more of the client stations using thecalculated times-of-flight. For example, the client station 154-1 usestriangulation techniques to calculate an estimated positions of theclient station 154-1 using the calculated time-of-flight. In someembodiments, the client station 154-1 calculates an estimated positionsof the client station also using the recorded angles AoD_(1,k),AoA_(1,k), AoD_(2,k), and AoA_(2,k). For example, the recorded anglesAoD_(1,k), AoA_(1,k), AoD_(2,k), and AoA_(2,k) are used as part of atriangulation algorithm for determining a position of the client station154-1.

Responsive to receipt of the FB frames 282, the client station 154generate an UL MU transmission 286 (which may be an UL OFDMAtransmission or an UL MU MIMO transmission) that includes respective ACKframes 290 from respective client stations, according to an embodiment.The client station 154 transmit as part of the UL MU transmission 286 adefined time period after an end of the DL transmission 278. In anembodiment, the defined time period is SIFS. In other embodiments,another suitable time period is utilized.

FIG. 2D is a timing diagram of the example MU ranging measurementexchange 270 of FIG. 2C.

In some embodiment, the MU ranging measurement exchange 200 of FIG. 2Aand the MU ranging measurement exchange 270 of FIG. 2C are combined. Forexample, the DL FB exchange 274 of FIG. 2C is included in the MU rangingmeasurement exchange 200 of FIG. 2A after the UL FB exchange 212,according to an embodiment. As another example, the DL FB exchange 274of FIG. 2C is included in the MU ranging measurement exchange 200 ofFIG. 2A after the DL NDP transmission 208 and before the UL FB exchange212, according to another embodiment.

FIG. 2E is a diagram of another example MU ranging measurement exchange294 in another MU ranging measurement procedure, according to anembodiment.

The MU ranging measurement exchange 294 corresponds to an AP-initiatedMU ranging measurement exchange, according to an embodiment. The MUranging measurement exchange 294 is similar to the MU rangingmeasurement exchange 270 of FIG. 2C, but further includes the UL FBexchange 212 of FIG. 2A after DL FB exchange 274. In an embodiment, theuplink UL NDP frame exchange 204, the DL NDP transmission portion 208,the DL FB exchange 274, and the UL FB exchange 212 occur within a singleTXOP. In another embodiment, the uplink UL NDP frame exchange 204, theDL NDP transmission portion 208, the DL FB exchange 274, and the UL FBexchange 212 do not occur within a single TXOP.

FIG. 3 is a diagram of another example MU ranging measurement exchange300 in another MU ranging measurement procedure, according to anembodiment. The MU ranging measurement exchange 300 is described in thecontext of the example network 110 merely for explanatory purposes. Insome embodiments, signals illustrated in FIG. 3 are generated by othersuitable communication devices in other suitable types of wirelessnetworks.

The MU ranging measurement exchange 300 corresponds to an AP-initiatedMU ranging measurement exchange, according to an embodiment. The MUranging measurement exchange 300 is similar to the MU rangingmeasurement exchange 200 of FIG. 2A, but the DL PPDU 252 (with ACKs 256)of FIG. 2A is omitted. In an embodiment, the uplink UL NDP frameexchange 204, the DL NDP transmission portion 208, and the DL FBexchange 274 occur within a single TXOP. In another embodiment, theuplink UL NDP frame exchange 204, the DL NDP transmission portion 208,and the DL FB exchange 274 do not occur within a single TXOP.

In the scenario illustrated in FIG. 3, the AP 114 correctly receivesPPDU 248-1 from STA1 and PPDU 248-2 from STA2 as part of the UL MUtransmission 244. In an embodiment, the AP 114 does not generate andtransmit any ACK frame to STA1 or STA2 even when successfully receivingthe UL PPDUs 3248 from STA1 and STA2.

In the scenario illustrated in FIG. 3, the AP 114 did not correctlyreceive PPDU 248-3 from STA3 and PPDU 248-4 from STA4 (as part of the ULMU transmission 244) due to, for example, a collision (e.g.,interference). The AP 114 (e.g., the MAC processor 126) determines thatFB from STA3 and STA4 was not successfully received in the UL MUtransmission 244. In response, the AP 114 initiates a second UL FBexchange 304 by generating and transmitting a DL PPDU 308 a defined timeperiod after an end of the UL MU transmission 244. In an embodiment, thedefined time period is SIFS. In other embodiments, another suitable timeperiod is utilized.

The PPDU 308 includes a trigger frame to cause the STA3 and STA4 tosimultaneously transmit, as part of an UL MU transmission 312, uplinkPPDUs 316 that include ranging measurement feedback. The trigger framein the PPDU 308 is similar to the trigger frame in the PPDU 240, andcauses STA3 and STA4 to begin simultaneously transmitting the UL MUtransmission 312 a defined time period after an end of the PPDU 308. Inan embodiment, the defined time period is SIFS. In other embodiments,another suitable time period is utilized.

The UL MU transmission 312 (which may be an UL OFDMA transmission or anUL MU-MIMO transmission) includes UL PPDUs 316 from STA3 and STA4. TheUL PPDUs 316 are illustrated in FIG. 3 as being transmitted in differentfrequency bandwidth portions. In some embodiments, the UL PPDUs 316 aretransmitted within a same frequency band (e.g., the UL PPDUs 316 spanthe same frequency band) using different spatial streams (e.g., the ULPPDUs 316 are transmitted using MU-MIMO).

The UL PPDUs 316 correspond to uplink ranging measurement feedbackpackets from STA3 and STA4. The PPDUs 316 respectively include therecorded times t_(1,k) and t_(4,k). In some embodiments, one or both ofthe PPDUs 316 respectively includes the recorded angles AoD_(1,k) andAoA_(2,k). In some embodiments, the PPDUs 316 optionally also includerespective channel estimate information determined by STA3 and STA4based on reception of the DL NDPs 236.

In an embodiment, the AP 114 does not generate and transmit any ACKframe to STA3 or STA4 even when successfully receiving the UL PPDUs 316from STA3 and STA4.

In another embodiment, the MU ranging measurement exchange 300 furtherincludes the DL FB exchange 274 prior to the UL FB exchange 212.

As discussed above, UL FB PPDUs 248 may include, in addition to recordedtimes t_(1,k) and t_(4,k), one or more of i) the recorded anglesAoD_(1,k), ii) the recorded angles AoA_(2,k), and iii) channel estimateinformation determined by client stations 154 based on reception of theDL NDPs 236. In some embodiments, channel estimate information can beconveyed in different granularities. For example, in some embodiments,one respective channel measurement is provided for each OFDM tone, orone respective channel measurement is provided for each group of n OFDMtones, where n is an integer greater than one. Sending one respectivechannel measurement for each group of n OFDM tones requires less totalchannel estimate information to be conveyed across the wireless channelmedium, as opposed to sending one respective channel measurement foreach OFDM tone. In some embodiments, a channel measurement can bequantized to different numbers of bits. For instance, a channelmeasurement can represented using m bits, where m is a positive integerchosen from a suitable set of different positive integers correspondingto different quantization granularities. Sending channel measurementsthat are each represented using m bits requires less total channelestimate information to be conveyed across the wireless channel medium,as opposed to sending channel measurements that are each representedusing m+2 bits, for example. Thus, different granularities channelestimate information correspond to different value(s) of one or both ofn and m, according to an embodiment.

In some embodiments, the AP 114 (e.g., the MAC processor 126) determinesthat one or more client stations 154 are to include, in one or more ofthe UL FB PPDUs 248/316, one or more of i) recorded angle(s) AoD_(1,k),ii) recorded angle(s) AoA_(2,k), and iii) channel estimate informationdetermined by client station(s) 154 based on reception of the DL NDPs236. In some embodiments, the AP 114 (e.g., the MAC processor 126)determines the granularity(ies) of channel estimate information to beincluded in one or more of the UL FB PPDUs 248/316. In some embodiments,the AP 114 (e.g., the MAC processor 126) generates one or more MACframes that include information configured to cause one or more of theclient stations 154 to include, in one or more of the UL FB PPDUs248/316, one or more of i) recorded angle(s) AoD_(1,k), ii) recordedangle(s) AoA_(2,k), and iii) channel estimate information determined byclient station(s) 154 based on reception of the DL NDPs 236. In someembodiments, contents of the sounding feedback, e.g., time stamp(s),AoA, AoD, channel estimation information, etc., is decided during an NDPsounding negotiation that occurs prior to the MU ranging measurementexchange 300. In some embodiments, contents of the sounding feedback isspecified in a trigger frame (e.g., trigger frame 216, 240 and/or 308)or an NDP Announcement frame (e.g., NDPA 228). If the one or more of theclient stations 154 are to include, in one or more of the UL FB PPDUs248/316, channel estimate information, the one or more MAC frames mayinclude information that indicates the granularity(ies) of the channelestimate information to be included in one or more of the UL FB PPDUs248/316, according to some embodiments. The AP 114 then transmits theone or more MAC frames prior to the MU ranging measurement exchange200/300. In some embodiments, granularity(ies) of the channel estimationinformation is decided during an NDP sounding negotiation that occursprior to the MU ranging measurement exchange 300. In some embodiments,granularity(ies) of the channel estimation information is specified in atrigger frame (e.g., trigger frame 216, 240 and/or 308) or an NDPAnnouncement frame (e.g., NDPA 228).

In some embodiments, the AP 114 (e.g., the MAC processor 126) generatesone or more MAC frames that include information indicating channelresources (e.g., channel frequency bandwidth, spatial streams, etc.)allocated to the client stations 154 for transmitting the UL FB PPDUs248/316. In some embodiments, the AP 114 (e.g., the MAC processor 126)allocates channel resources to the client stations 154 so that theclient station 154 can include the determined information (e.g., arecorded angle AoD_(1,k), a recorded angle AoA_(2,k), channel estimateinformation, channel estimate information at a particular granularity,etc.) in the UL FB PPDUs 248/316, given the channel resources (e.g.,channel frequency bandwidth, spatial streams, etc.) allocated to theclient stations 154. The AP 114 then transmits the one or more MACframes prior to the MU ranging measurement exchange 200/300. In someembodiments, the AP 114 (e.g., the MAC processor 126) includes theinformation indicating channel resources (e.g., channel frequencybandwidth, spatial streams, etc.) allocated to the client stations 154for transmitting the UL FB PPDUs 248/316 in the trigger frame 216, theNDPA 228, the trigger frame 240, and/or the trigger frame 308.

In some embodiments, the AP is configured to allocate sufficient channelmedium resources for a client station 154 to report the rangingfeedback. In some embodiments, a client station 154 (e.g., the MACprocessor 166) determines whether the information (e.g., a recordedangle AoD_(1,k), a recorded angle AoA_(2,k), channel estimateinformation, channel estimate information at a particular granularity,etc.) requested by the AP 114 can be included within a single UL FB PPDU248/316 given the channel resources (e.g., channel frequency bandwidth,spatial streams, etc.) allocated to the client station 154 by the AP114. When the client station 154 (e.g., the MAC processor 166)determines that the information (e.g., a recorded angle AoD_(1,k), arecorded angle AoA_(2,k), channel estimate information, channel estimateinformation at a particular granularity, etc.) requested by the AP 114cannot be included within a single UL FB PPDU 248/316 given the channelresources (e.g., channel frequency bandwidth, spatial streams, etc.)allocated to the client station 154 by the AP 114, the client station154 (e.g., the MAC processor 166) generates a MAC frame (e.g., a qualityof service (QoS) null frame or another suitable MAC frame) to requestadditional channel resources (e.g., more channel frequency bandwidth,one or more additional spatial streams, etc.) for transmitting the UL FBPPDU 248/316, and the client station 154 transmits the MAC frame priorto the MU ranging measurement exchange 200/300, according to anembodiment. When the client station 154 (e.g., the MAC processor 166)determines that the information (e.g., a recorded angle AoD_(1,k), arecorded angle AoA_(2,k), channel estimate information, channel estimateinformation at a particular granularity, etc.) requested by the AP 114cannot be included within a single UL FB PPDU 248/316 given the channelresources (e.g., channel frequency bandwidth, spatial streams, etc.)allocated to the client station 154 by the AP 114, the client station154 (e.g., the MAC processor 166) determines that the requestedinformation is to be fragmented across multiple UL PPDUs such that onlysubset of the requested information is included in the UL FB PPDU248/316, according to an embodiment.

In some embodiments, the client station 154 (e.g., the MAC processor166) determines (e.g., via negotiation with the AP 114, as specified bythe NDPA 228 and/or the DL Trigger frame for MU Ranging 216, etc.)whether the client station 154 is to include, in the UL FB PPDUs248/316, one or more of i) recorded angle(s) AoD_(1,k), ii) recordedangle(s) AoA_(2,k), and iii) channel estimate information determined byclient station 154 based on reception of the DL NDP 236. In someembodiments, the client station 154 (e.g., the MAC processor 166)determines the granularity of channel estimate information to beincluded in the UL FB PPDUs 248/316. In some embodiments, the clientstation 154 (e.g., the MAC processor 166) determines whether the clientstation 154 is to include, in the UL FB PPDUs 248/316, one or more of i)recorded angle(s) AoD_(1,k), ii) recorded angle(s) AoA_(2,k), iii)channel estimate information, and/or iv) the granularity of the channelestimate information so that the determined information can be includedin the UL FB PPDUs 248/316, given the channel resources (e.g., channelfrequency bandwidth, spatial streams, etc.) allocated to the clientstation 154 by the AP 114.

In some embodiments, the AP 114 and the client station 154 negotiatewhether the client station 154 is to include, in the UL FB PPDUs248/316, one or more of i) recorded angle(s) AoD_(1,k), ii) recordedangle(s) AoA_(2,k), iii) channel estimate information, and/or iv) thegranularity of the channel estimate information prior to the MU rangingmeasurement exchange 200/300. For example, in an embodiment, negotiatingincludes the AP 114 (e.g., the MAC processor 126) generating one or moreMAC frames (e.g., one or more NDP ranging negotiation response frames)with information indicating requested types of information to beincluded and/or requested granularities, and the AP 114 transmits theone or more MAC frames to the client station 154 prior to the MU rangingmeasurement exchange 200/300. Similarly, in an embodiment, negotiatingincludes the client station 154 (e.g., the MAC processor 166) generatingone or more MAC frames (e.g., one or more NDP ranging negotiationrequest frames) with information indicating proposed types ofinformation to be included and/or requested granularities, and theclient station 154 transmits the one or more MAC frames to the AP 114prior to the MU ranging measurement exchange 200/300. In someembodiment, the client station 154 generates one or more MAC frames(e.g., one or more NDP ranging negotiation request frames) withinformation indicating its supported type(s) and/or granularity(ies),and the AP 114 selects, from the supported type(s) and/orgranularity(ies), a type and/or a granularity for the STA to report itsmeasurement feedback, and transmits one or more MAC frames (e.g., NDPranging negotiation response frames) with the selected type and/or agranularity.

FIG. 4 is a flow diagram of an example method 400 for performing aranging measurement exchange, according to an embodiment. In someembodiments, the network interface device 122 of FIG. 1 is configured toimplement the method 400. The method 400 is described in the context ofthe network interface device 122 merely for explanatory purposes and, inother embodiments, the method 400 is implemented by another suitablecommunication device. Additionally, the method 400 is described in thecontext of the ranging exchange 200 of FIG. 2A merely for explanatorypurposes and, in other embodiments, the method 400 is implemented inconnection with other suitable ranging exchanges.

At block 404, a first communication device determines (e.g., the networkinterface device 122 determines, e.g., the MAC processor 126 of thenetwork interface device 122 determines; etc.) information that a secondcommunication device (e.g., the client station 154-1) is to provide inan uplink feedback transmission (e.g., the UL FB PPDU 248/316) to thefirst communication device, wherein the uplink feedback transmission isa part of the ranging measurement exchange. In an embodiment, the MACprocessor 126 determines whether the client station 154 is to include,in the UL FB PPDU 248/316, one or more of i) the recorded angleAoD_(1,k), ii) the recorded angle AoA_(2,k), iii) channel estimateinformation, and/or iv) the granularity of the channel estimateinformation.

In some embodiments, block 404 comprises the first communication devicedetermining the information that the second communication device is toprovide in the uplink feedback transmission without negotiating with thesecond communication device regarding which information (and/or, if theinformation includes channel estimate information, a granularity of thechannel estimate information) the second communication device is toprovide in the uplink feedback transmission. In other embodiments, block404 comprises the first communication device negotiating with the secondcommunication device regarding which information (and/or, if theinformation includes channel estimate information, a granularity of thechannel estimate information) the second communication device is toprovide in the uplink feedback transmission.

At block 408, the first communication device transmits (e.g., thenetwork interface device 122 transmits, etc.) to the secondcommunication device an indication or indications of the informationdetermined at block 404. In an embodiment, the network interface device122 includes an indication or indications of the information determinedat block 404 in the trigger frame 216 (FIG. 2A). In an embodiment, thenetwork interface device 122 includes an indication or indications ofthe information determined at block 404 in the NDPA 228 (FIG. 2A). In anembodiment, the network interface device 122 includes an indication orindications of the information determined at block 404 in the triggerframe 240 (FIG. 2A). In an embodiment, the network interface device 122includes an indication or indications of the information determined atblock 404 in a PPDU transmitted prior to the ranging measurementexchange 200, e.g., in one or more NDP ranging negotiation responseframes or one or more NDP ranging negotiation request frames.

At block 412, the first communication device performs the rangingmeasurement exchange with the second communication device. Block 412includes the first communication device receiving, in an uplink feedbacktransmission from the second communication device, wherein the uplinkfeedback transmission includes the information determined at block 404.In an embodiment, block 412 includes performing the downlinktransmissions discussed with respect to FIG. 2A, and receiving theuplink transmissions discussed with respect to FIG. 2A. In anembodiment, block 412 includes receiving the information determined atblock 404 in an UL FB PPDU 248.

In an embodiment, the method 400 is performed for a group of secondcommunication devices (e.g., client stations). For example thedetermination of block 404 is performed for a group of client stations,the indication(s) transmitted at block 408 are transmitted to the groupof communication devices, and the determined information is received inan UL MU transmission, such as the UL MU transmission 244 (FIG. 2A).

FIG. 5 is a flow diagram of another example method 500 for performing aranging measurement exchange, according to an embodiment. In someembodiments, the network interface device 162 of FIG. 1 is configured toimplement the method 500. The method 500 is described in the context ofthe network interface device 162 merely for explanatory purposes and, inother embodiments, the method 500 is implemented by another suitablecommunication device. Additionally, the method 500 is described in thecontext of the ranging exchange 200 of FIG. 2A merely for explanatorypurposes and, in other embodiments, the method 500 is implemented inconnection with other suitable ranging exchanges.

At block 504, a first communication device determines (e.g., the networkinterface device 162 determines, e.g., the MAC processor 166 of thenetwork interface device 162 determines; etc.) information that thefirst communication device is to provide in an uplink feedbacktransmission (e.g., the UL FB PPDU 248/316) to a second communicationdevice (e.g., the AP 114), wherein the uplink feedback transmission is apart of the ranging measurement exchange. In an embodiment, the MACprocessor 166 determines whether the UL FB PPDU 248/316 is to includeone or more of i) the recorded angle AoD_(1,k), ii) the recorded angleAoA_(2,k), iii) channel estimate information, and/or iv) the granularityof the channel estimate information.

In some embodiments, block 504 comprises the first communication devicedetermining the information that is to be provided in the uplinkfeedback transmission without being instructed by, and withoutnegotiating with, the second communication device regarding whichinformation (and/or, if the information includes channel estimateinformation, a granularity of the channel estimate information) is to beprovided in the uplink feedback transmission.

In another embodiment, the method 500 is performed in conjunction withthe method 400, and block 504 comprises receiving a transmission fromthe second communication device (e.g., corresponding to the transmissionof block 408 of FIG. 4), where the transmission includes anindication(s) of which information (and/or, if the information includeschannel estimate information, a granularity of the channel estimateinformation) is to be provided in the uplink feedback transmission. Invarious embodiments, the received transmission is the trigger 216, theNDPA 228, the trigger 240, or a transmission prior to the rangingmeasurement exchange 200. In another embodiment, the method 500 isperformed in conjunction with the method 400, and block 504 comprisesnegotiating with the second communication device regarding whichinformation (and/or, if the information includes channel estimateinformation, a granularity of the channel estimate information) is to beprovided in the uplink feedback transmission.

At block 508, the first communication device performs the rangingmeasurement exchange with the second communication device. Block 508includes the first communication device transmitting, in an uplinkfeedback transmission, the information determined at block 504. In anembodiment, block 508 includes performing the uplink transmissionsdiscussed with respect to FIG. 2A, and receiving the downlinktransmissions discussed with respect to FIG. 2A. In an embodiment, block508 includes transmitting the information determined at block 504 in anUL FB PPDU 248.

Referring again to FIG. 2A, one or more client stations will need moretime to prepare the feedback information included in one or morerespective UL FB PPDUs 248 than is provided by the example sequenceillustrated in FIG. 2A, in some embodiments. Thus, in some embodiments,the UL NDP frame exchange 204 and the DL NDP transmission portion 208are performed during a first TXOP, and the UL FB exchange 212 isperformed during a separate second TXOP. In an embodiment, the networkinterface device 122 determines (e.g., the MAC processor 126 determines)an earliest start time of the second TXOP such that client stations 154that will participate in the UL MU transmission 244 will have sufficienttime to prepare the feedback information to be included in the UL MUtransmission 244. In an embodiment, client stations 154 report (e.g.,transmit to the AP 114) respective times required by the client stations154 to prepare the feedback information to be included in the UL MUtransmission 244, and the AP 114 (e.g., the MAC processor 126) uses thereported times to determine an earliest start time of the second TXOPsuch that client stations 154 that will participate in the UL MUtransmission 244 will have sufficient time to prepare the feedbackinformation to be included in the UL MU transmission 244. In anembodiment, the network interface device 122 determines (e.g., the MACprocessor 126 determines) an earliest transmission time of the triggerframe 240 during the second TXOP such that client stations 154 that willparticipate in the UL MU transmission 244 will have sufficient time toprepare the feedback information to be included in the UL MUtransmission 244. In an embodiment, client stations 154 report (e.g.,transmit to the AP 114) respective times required by the client stations154 to prepare the feedback information to be included in the UL MUtransmission 244, and the AP 114 (e.g., the MAC processor 126determines) uses the reported times to determine an earliest transmittime of the trigger frame 240 such that client stations 154 that willparticipate in the UL MU transmission 244 will have sufficient time toprepare the feedback information to be included in the UL MUtransmission 244.

In an embodiment, client stations 154 report (e.g., transmit to the AP114) respective times required by the client stations 154 to prepare thefeedback information to be included in the UL MU transmission 244 in acapabilities information element included in a MAC frame such as anassociation request frame, a reassociation request frame, an NDPnegotiation request frame, an NDP negotiation response frame, etc. In anembodiment, the capabilities information element includes a field forreporting a times required by a station to prepare the feedbackinformation to be included in a PPDU related to UL ranging measurementfeedback.

In an embodiment, the AP 114 determines (e.g., the MAC processor 126determines) a maximum time among the respective times required by theclient stations 154 to prepare the feedback information to be includedin the UL MU transmission 244, and the AP 114 uses (e.g., the MACprocessor 126 uses) the maximum time to determine an earliest start timeof the second TXOP and/or an earliest transmission time of the triggerframe 240. The AP 114 then determines (e.g., the MAC processor 126determines) when to initiate transmission of the trigger frame 240 basedon the determined earliest start time of the second TXOP and/or theearliest transmission time of the trigger frame 240.

FIG. 6 is a diagram of another example MU ranging measurement exchange600 in another MU ranging measurement procedure, according to anembodiment. The MU ranging measurement exchange 600 is described in thecontext of the example network 110 merely for explanatory purposes. Insome embodiments, signals illustrated in FIG. 6 are generated by othersuitable communication devices in other suitable types of wirelessnetworks.

The MU ranging measurement exchange 600 corresponds to an AP-initiatedMU ranging measurement exchange, according to an embodiment. The MUranging measurement exchange 600 is similar to the MU rangingmeasurement exchange 200 of FIG. 2A, but an UL FB frame exchange 604does not begin SIFS after the DL MU transmission 232 as in the MUranging measurement exchange 200 of FIG. 2A. In an embodiment, theuplink UL NDP frame exchange 204 and the DL NDP transmission portion 208occur within a first TXOP 608, whereas the UL FB frame exchange 604occurs within a second TXOP 612.

Responsive to receipt of the UL FB PPDUs 248, the AP 114 generates andtransmits a DL PPDU 620 that includes an MU block acknowledgment (M-BA)frame 624 that acknowledges the PPDUs 248, according to an embodiment.In another embodiment, the DL PPDU 620 is an MU transmission (e.g.,OFDMA and/or MU MIMO) with respective ACK frames for respective STAs. Inanother embodiment, the DL PPDU 620 includes a single ACK frame thatacknowledges receipt of multiple PPDUs 248 from multiple STAs. The AP114 transmits the DL PPDU 252 a defined time period after an end of theUL transmission 244. In an embodiment, the defined time period is SIFS.In other embodiments, another suitable time period is utilized.

In some embodiments, the AP 114 does not generate and transmit the DLPPDU 620 even when the AP 114 successfully receives the UL PPDUs 248,according to an embodiment. Thus, in some embodiments, the DL PPDU 620is omitted from the procedure 600.

In an embodiment, the network interface device 122 determines (e.g., theMAC processor 126 determines) a start time of the second TXOP 612 suchthat client stations 154 that will participate in the UL MU transmission244 will have sufficient time to prepare the feedback information to beincluded in the UL MU transmission 244. In an embodiment, the networkinterface device 122 determines (e.g., the MAC processor 126 determines)a transmission time of the trigger 240 during the second TXOP 612 suchthat client stations 154 that will participate in the UL MU transmission244 will have sufficient time to prepare the feedback information to beincluded in the UL MU transmission 244.

In an embodiment, the network interface device 122 determines (e.g., theMAC processor 126 determines) a delay period after the DL NDPtransmission 208 such that client stations 154 that will participate inthe UL MU transmission 244 will have sufficient time to prepare thefeedback information to be included in the UL MU transmission 244. In anembodiment, the AP 114 determines (e.g., the MAC processor 126determines) a maximum time among the respective times required by theclient stations 154 to prepare the feedback information to be includedin the UL MU transmission 244, and the AP 114 uses (e.g., the MACprocessor 126 uses) the maximum time to determine the delay period. TheAP 114 then determines (e.g., the MAC processor 126 determines) when toinitiate transmission of the trigger frame 240 based on the determineddelay period.

In another embodiment, the MU ranging measurement exchange 600 furtherincludes, in the TXOP 612, the DL FB exchange 274 prior to the UL FBexchange 604.

In some embodiments, another UL FB exchange (not shown) occurs duringthe TXOP 608, after the uplink UL NDP frame exchange 204 and the DL NDPtransmission portion 208, but the feedback provided in the other UL FBexchange is for a previous ranging measurement exchange (not shown) thatoccurred prior to the UL NDP frame exchange 204 and the DL NDPtransmission portion 208 in the TXOP 608.

Referring again to FIG. 2A, the UL NDP frame exchange 204, the DL NDPtransmission portion 208, and the UL FB exchange 212 are performedduring a single TXOP, but a delay between the DL NDP transmissionportion 208 and the UL FB exchange 212 is provided so that the clientstations 154 have more time to prepare feedback information to beincluded in the UL MU transmission 244, according to an embodiment.

Referring now to FIGS. 2A and 6, in another embodiment, the UL FBexchange 212 occurs in the TXOP 608, but includes feedback informationfor a previous ranging measurement exchange (not shown) that occurredprior to the UL NDP frame exchange 204 and the DL NDP transmissionportion 208.

FIG. 7 is a diagram of another example MU ranging measurement exchange700 in another MU ranging measurement procedure, according to anembodiment. The MU ranging measurement exchange 700 is described in thecontext of the example network 110 merely for explanatory purposes. Insome embodiments, signals illustrated in FIG. 7 are generated by othersuitable communication devices in other suitable types of wirelessnetworks.

The MU ranging measurement exchange 700 corresponds to an AP-initiatedMU ranging measurement exchange, according to an embodiment. The MUranging measurement exchange 700 is similar to the MU rangingmeasurement exchange 200 of FIG. 2A, but an UL FB frame exchange 704does not begin SIFS after the DL MU transmission 232 as in the MUranging measurement exchange 200 of FIG. 2A. In an embodiment, the UL FBframe exchange 704 occurs after a delay period 708 after an end of theDL NDP transmission 208.

In an embodiment, the network interface device 122 determines (e.g., theMAC processor 126 determines) the delay period 708 such that clientstations 154 that will participate in the UL MU transmission 244 willhave sufficient time to prepare the feedback information to be includedin the UL MU transmission 244. In an embodiment, the AP 114 determines(e.g., the MAC processor 126 determines) a maximum time among therespective times required by the client stations 154 to prepare thefeedback information to be included in the UL MU transmission 244, andthe AP 114 uses (e.g., the MAC processor 126 uses) the maximum time todetermine the delay period 708.

In an embodiment, the network interface device 122 transmits a PPDU thatis not related to the MU ranging measurement exchange 700 during thedelay period 708 if the delay period 708 is sufficient to transmit thePPDU (and to receive an acknowledgment of the PPDU if the acknowledgmentof the PPDU is required). In an embodiment, the network interface device122 transmits a PPDU that includes a MAC data frame, a MAC managementframe, an MAC control frame, etc., to one of the client station 154participating in the MU ranging measurement exchange 700. In anembodiment, the network interface device 122 transmits a PPDU thatincludes a MAC data frame, a MAC management frame, an MAC control frame,etc., to a client station 154 that is not participating in the MUranging measurement exchange 700. In an embodiment, the networkinterface device 122 transmits a PPDU that is part of an MU rangingmeasurement exchange with another group of client stations that are notparticipating in the MU ranging measurement exchange 700.

In another embodiment, the MU ranging measurement exchange 700 furtherincludes, after the delay period 708, the DL FB exchange 274 prior tothe UL FB exchange 604.

Referring again to FIG. 2C, the AP 114 will need more time to preparethe feedback information included in DL FB PPDUs 282 than is provided bythe example sequence illustrated in FIG. 2C, in some scenarios and/orembodiments. Thus, in some embodiments, the UL NDP frame exchange 204and the DL NDP transmission portion 208 are performed during a firstTXOP, and the DL FB exchange 274 is performed during a separate secondTXOP. In an embodiment, the network interface device 122 determines(e.g., the MAC processor 126 determines) an earliest start time of thesecond TXOP such that the AP 114 will have sufficient time to preparethe feedback information to be included in the DL MU transmission 278.In an embodiment, the network interface device 122 determines (e.g., theMAC processor 126 determines) an earliest transmission time of the DL MUtransmission 278 during the second TXOP such that the AP 114 will havesufficient time to prepare the feedback information to be included inthe DL MU transmission 278.

In an embodiment, the network interface device 122 determines (e.g., theMAC processor 126 determines) a delay period after the DL NDPtransmission 208 such that the AP 114 will have sufficient time toprepare the feedback information to be included in the DL MUtransmission 278. The AP 114 then determines (e.g., the MAC processor126 determines) when to initiate transmission of the DL MU transmission278 based on the determined delay period.

FIG. 8 is a diagram of another example MU ranging measurement exchange800 in another MU ranging measurement procedure, according to anembodiment. The MU ranging measurement exchange 800 is described in thecontext of the example network 110 merely for explanatory purposes. Insome embodiments, signals illustrated in FIG. 8 are generated by othersuitable communication devices in other suitable types of wirelessnetworks.

The MU ranging measurement exchange 800 corresponds to an AP-initiatedMU ranging measurement exchange, according to an embodiment. The MUranging measurement exchange 800 is similar to the MU rangingmeasurement exchange 270 of FIG. 2C, but a DL FB frame exchange 804 doesnot begin SIFS after the DL MU transmission 232 as in the MU rangingmeasurement exchange 270 of FIG. 2C. In an embodiment, the UL NDP frameexchange 204 and the DL NDP transmission portion 208 occur within afirst TXOP 808, whereas the DL FB frame exchange 804 occurs within asecond TXOP 812.

Responsive to receipt of the DL FB PPDUs 278, the client stationstransmit an UL MU transmission 820 that includes an MU blockacknowledgment (M-BA) frame 824 that acknowledges the PPDUs 282,according to an embodiment. In another embodiment, the UL MUtransmission 820 is an MU transmission (e.g., OFDMA and/or MU MIMO) withrespective ACK frames from respective STAs. The client stations 154transmit the UL MU transmission 820 a defined time period after an endof the DL transmission 278. In an embodiment, the defined time period isSIFS. In other embodiments, another suitable time period is utilized.

In some embodiments, the client station 154 do not transmit the UL MUtransmission 820 even when the client station 154 successfully receivesthe DL PPDUs 282, according to an embodiment. Thus, in some embodiments,the UL MU transmission 820 is omitted from the procedure 800.

In another embodiment, the MU ranging measurement exchange 800 furtherincludes, in the TXOP 812, the UL FB exchange 212 after the DL FBexchange 804.

In some embodiments, another UL FB exchange (not shown) occurs duringthe TXOP 808, after the uplink UL NDP frame exchange 204 and the DL NDPtransmission portion 208, but the feedback provided in the other UL FBexchange is for a previous ranging measurement exchange (not shown) thatoccurred prior to the UL NDP frame exchange 204 and the DL NDPtransmission portion 208 in the TXOP 808.

In an embodiment, the network interface device 122 determines (e.g., theMAC processor 126 determines) a start time of the second TXOP 812 suchthat the network interface device 122 will have sufficient time toprepare the feedback information to be included in the DL MUtransmission 278. In an embodiment, the network interface device 122determines (e.g., the MAC processor 126 determines) a transmission timeof the DL MU transmission 278 during the second TXOP 612 such that thenetwork interface device 122 will have sufficient time to prepare thefeedback information to be included in the DL MU transmission 278.

In an embodiment, the network interface device 122 determines (e.g., theMAC processor 126 determines) a delay period after the DL NDPtransmission 208 such that the AP 114 will have sufficient time toprepare the feedback information to be included in the DL MUtransmission 278. The AP 114 then determines (e.g., the MAC processor126 determines) when to initiate transmission of the DL MU transmission278 based on the determined delay period.

Referring again to FIG. 2C, the UL NDP frame exchange 204, the DL NDPtransmission portion 208, and the DL FB exchange 274 are performedduring a single TXOP, but a delay between the DL NDP transmissionportion 208 and the DL FB exchange 274 is provided so that the networkinterface device 122 has more time to prepare feedback information to beincluded in the DL MU transmission 278, according to an embodiment.

Referring now to FIGS. 2C and 8, in another embodiment, the DL FBexchange 274 occurs in the TXOP 808, but includes feedback informationfor a previous ranging measurement exchange (not shown) that occurredprior to the UL NDP frame exchange 204 and the DL NDP transmissionportion 208.

FIG. 9 is a diagram of another example MU ranging measurement exchange900 in another MU ranging measurement procedure, according to anembodiment. The diagram 900 is described in the context of the examplenetwork 110 merely for explanatory purposes. In some embodiments,signals illustrated in FIG. 9 are generated by other suitablecommunication devices in other suitable types of wireless networks.

The MU ranging measurement exchange 900 corresponds to an AP-initiatedMU ranging measurement exchange, according to an embodiment. The MUranging measurement exchange 900 is similar to the MU rangingmeasurement exchange 270 of FIG. 2C, but a DL FB frame exchange 904 doesnot begin SIFS after the DL MU transmission 232 as in the MU rangingmeasurement exchange 270 of FIG. 2C. In an embodiment, the DL FB frameexchange 904 occurs after a delay period 908 after an end of the DL NDPtransmission 208. In an embodiment, UL NDP exchange 204, the DL NDPtransmission 208, and the DL FB frame exchange 904 occurs in one TXOP.

In an embodiment, the network interface device 122 determines (e.g., theMAC processor 126 determines) the delay period 908 such that the networkinterface device 122 will have sufficient time to prepare the feedbackinformation to be included in the DL MU transmission 278.

In an embodiment, the network interface device 122 transmits a PPDU thatis not related to the MU ranging measurement exchange 900 during thedelay period 908 if the delay period 908 is sufficient to transmit thePPDU (and to receive an acknowledgment of the PPDU if the acknowledgmentof the PPDU is required). For example, in an embodiment, the networkinterface device 122 transmits a PPDU that includes a MAC data frame, aMAC management frame, an MAC control frame, etc., to one of the clientstation 154 participating in the MU ranging measurement exchange 900. Asanother example, in an embodiment, the network interface device 122transmits a PPDU that includes a MAC data frame, a MAC management frame,an MAC control frame, etc., to a client station 154 that is notparticipating in the MU ranging measurement exchange 900. As anotherexample, in an embodiment, the network interface device 122 transmits aPPDU that is part of an MU ranging measurement exchange with anothergroup of client stations that are not participating in the MU rangingmeasurement exchange 900.

In another embodiment, the MU ranging measurement exchange 900 furtherincludes, after the delay period 908, the UL FB exchange 212 after theDL FB exchange 904.

FIG. 10 is a flow diagram of an example method 1000 for performing aranging measurement exchange, according to an embodiment. In someembodiments, the network interface device 122 of FIG. 1 is configured toimplement the method 1000. The method 1000 is described in the contextof the network interface device 122 merely for explanatory purposes and,in other embodiments, the method 1000 is implemented by another suitablecommunication device. Additionally, the method 1000 is described in thecontext of the ranging exchange 600 of FIG. 6, the ranging exchange 700of FIG. 7, the ranging exchange 800 of FIG. 8, and the ranging exchange900 of FIG. 9, merely for explanatory purposes and, in otherembodiments, the method 1000 is implemented in connection with othersuitable ranging exchanges.

At block 1004, a first communication device determines (e.g., thenetwork interface device 122 determines, e.g., the MAC processor 126 ofthe network interface device 122 determines; etc.) a delay periodassociated with a station generating feedback information as part of aranging measurement exchange. For example, with regard to UL feedback,the client stations 154 report (e.g., transmit to the AP 114) respectivetimes required by the client stations 154 to prepare feedbackinformation to be included in the UL MU transmission 244 in acapabilities information element included in a MAC frame such as anassociation request frame, a reassociation request frame, an NDPmeasurement negotiation request frame, etc., according to an embodiment,and the MAC processor 126 of the network interface device 122 determinesthe delay period based on the reported times. As another example, withregard to DL feedback, the MAC processor 126 retrieves a predetermineddelay period from a memory device, according to an embodiment.

At block 1008, the first communication device uses (e.g., the networkinterface device 122 uses, e.g., the MAC processor 126 of the networkinterface device 122 uses; etc.) the determined delay period todetermine when to initiate a feedback exchange that is part of theranging measurement exchange. For example, with respect to the exampleranging measurement exchange 600 of FIG. 6, the first communicationdevice determines (e.g., the network interface device 122 determines,e.g., the MAC processor 126 of the network interface device 122determines; etc.) when to initiate the TXOP 612 and/or initiatetransmission of the trigger frame 240, according to an embodiment. Asanother example, with respect to the example ranging measurementexchange 700 of FIG. 7, the first communication device determines (e.g.,the network interface device 122 determines, e.g., the MAC processor 126of the network interface device 122 determines; etc.) when to initiatetransmission of the trigger frame 240, according to an embodiment. Asanother example, with respect to the example ranging measurementexchange 800 of FIG. 8, the first communication device determines (e.g.,the network interface device 122 determines, e.g., the MAC processor 126of the network interface device 122 determines; etc.) when to initiatethe TXOP 812 and/or initiate transmission of the DL MU transmission 278,according to an embodiment. As another example, with respect to theexample ranging measurement exchange 900 of FIG. 9, the firstcommunication device determines (e.g., the network interface device 122determines, e.g., the MAC processor 126 of the network interface device122 determines; etc.) when to initiate transmission of the DL MUtransmission 278, according to an embodiment.

At block 1012, when the first communication device determines that thefeedback exchange is to be initiated, the first communication deviceinitiates (e.g., the network interface device 122 initiates, e.g., theMAC processor 126 of the network interface device 122 initiates; etc.)the feedback exchange. For example, with respect to the example rangingmeasurement exchange 600 of FIG. 6, the first communication deviceinitiates (e.g., the network interface device 122 initiates, e.g., theMAC processor 126 of the network interface device 122 initiates; etc.)transmission of the trigger frame 240 during the TXOP 612, according toan embodiment. As another example, with respect to the example rangingmeasurement exchange 700 of FIG. 7, the first communication deviceinitiates (e.g., the network interface device 122 initiates, e.g., theMAC processor 126 of the network interface device 122 initiates; etc.)transmission of the trigger frame 240 after the delay period 708,according to an embodiment. As another example, with respect to theexample ranging measurement exchange 800 of FIG. 8, the firstcommunication device initiates (e.g., the network interface device 122initiates, e.g., the MAC processor 126 of the network interface device122 initiates; etc.) transmission of the DL MU transmission 278 duringthe TXOP 812, according to an embodiment. As another example, withrespect to the example ranging measurement exchange 900 of FIG. 9, thefirst communication device initiates (e.g., the network interface device122 initiates, e.g., the MAC processor 126 of the network interfacedevice 122 initiates; etc.) transmission of the DL MU transmission 278after the delay period 908, according to an embodiment.

Various techniques described in connection with FIGS. 2A-D, and 3-5 canbe used in connection with various techniques described in connectionwith FIGS. 6-10.

Although techniques discussed above were described in the context ofmulti-user ranging measurement exchanges, the same or similar techniquescan also be used in the context of single-user ranging measurementexchanges.

FIG. 11A is a diagram of an example single-user (SU) ranging measurementexchange 1100 in an SU ranging measurement procedure, according to anembodiment. The diagram 1100 is described in the context of the examplenetwork 110 merely for explanatory purposes. In some embodiments,signals illustrated in FIG. 11A are generated by other suitablecommunication devices in other suitable types of wireless networks.

The SU ranging measurement exchange 1100 corresponds to aclient-initiated SU ranging measurement exchange, according to anembodiment. The SU ranging measurement exchange 100 includes an UL NDPtransmission portion 1104, a DL NDP transmission portion 1108, and a DLfeedback transmission portion 1112. In an embodiment, the uplink UL NDPtransmission portion 1104, the DL NDP transmission portion 1108, and theDL feedback portion 1112 occur within a single TXOP. In anotherembodiment, the uplink UL NDP transmission portion 1104, the DL NDPtransmission portion 1108, and the DL feedback transmission portion 1112do not occur within a single TXOP.

In the UL NDP transmission portion 1104, a first communication device(e.g., the client station 154) transmits a PPDU 1116 that includes an SUUL NDPA 1116 having information indicating the initiation of an SUranging measurement exchange. In an embodiment, the SU UL NDPA in thePPDU 1116 is a type of NDPA frame specifically for initiating an SUranging measurement exchange such as the SU ranging measurement exchange1100. The SU UL NDPA in the PPDU 1116 causes the AP 114 to be ready toreceive an NDP as part of an SU ranging measurement exchange.

The client station 154 then begins transmitting an NDP 1120 a definedtime period after an end of the PPDU 1116. In an embodiment, the definedtime period is SIFS. In other embodiments, another suitable time periodis utilized.

The UL NDP 1120 includes PHY preambles having one or more STFs, one ormore LTFs and one or more signal fields, in an embodiment. The UL NDP1120 omits a data portion.

When transmitting the UL NDP 1116, the client station 154 records a timet₁ at which the client station 154 began transmitting the UL NDP 1116.Similarly, when the AP 114 receives the UL NDP 1116, the AP 114 recordsa time t₂ at which the AP 114 began receiving the UL NDP 1116.

In some embodiments, when transmitting the UL NDP 1116, the clientstation 154 (e.g., a client station 154 with multiple antennas 174)records an angle of departure, AoD₁, at which the UL NDP 1116 left theantennas 178 of the client station 154. Similarly, when the AP 114receives the UL NDP 1116, the AP 114 records an angle of arrival, AoA₁,at which the UL NDP 1116 arrived at the antennas 138 of the AP 114.

FIG. 11B is a timing diagram of the example MU ranging measurementexchange 1100 of FIG. 11A. As illustrated in FIG. 11B, the clientstation 154 records the time t₁ at which the client station 154 begantransmitting the UL NDP 1120, and records the AoD₁ at which the UL NDP1120 left the antennas 178 of the client station 154. Additionally, theAP 114 records the time t₂ at which the AP 114 began receiving the ULNDP 1120, and the AoA₁, at which each UL NDP 1120 arrived at theantennas 138 of the AP 114.

Referring now to FIGS. 11A and 11B, generates a DL NDP 1128 and,responsive to the UL NDP 1120, the AP 114 begins transmitting the DL NDP1128 a defined time period after an end of the UL NDP 1120. In anembodiment, the defined time period is SIFS. In other embodiments,another suitable time period is utilized. The DL NDP 1128 includes a PHYpreamble having one or more STFs, one or more LTFs and one or moresignal fields, in an embodiment. The DL NDP 1128 omits a data portion.

When transmitting the DL NDP 1128, the AP 114 records a time t₃ at whichthe AP 114 began transmitting the DL NDP 1128. Similarly, when theclient station 154 receives the DL NDP 1128, the client station 154records a time t₄ at which the client station 154 began receiving the DLNDP 1128. As illustrated in FIG. 11B, the AP 114 records the time t₃ atwhich the AP 114 began transmitting the DL NDP 1128, and the clientstation 154 records the time t₄ at which the client station 154 beganreceiving the DL NDP 1128.

In some embodiments, when transmitting the DL NDP 1128, the AP 114records an AoD₂ at which the DL NDP 1128 left the antennas 138 of the AP114. Similarly, when the client station 154 receives the DL NDP 1128,the client station 154 records an AoA₂ at which the DL NDP 1128 arrivedat the antennas 178 of the client station 154.

In another embodiment, responsive to the UL NDP 1120, the AP 114 beginstransmitting a DL PPDU (not shown) that includes an NDPA frame a definedtime period after an end of the UL NDP 1120. In an embodiment, thedefined time period is SIFS. In other embodiments, another suitable timeperiod is utilized. The NDPA frame is configured to cause the clientstations 154 to be prepared to receive the DL NDP 1128 from the AP 114,according to an embodiment. The AP 114 then begins transmitting the DLNDP 1128 a defined time period after an end of the DL PPDU that includesthe NDPA frame. In an embodiment, the defined time period is SIFS. Inother embodiments, another suitable time period is utilized.

In an embodiment, the AP 114 transmits a DL PPDU 1132 a defined timeperiod after an end of the DL NDP 1128. In an embodiment, the definedtime period is SIFS. In other embodiments, another suitable time periodis utilized. The PPDU 1132 corresponds to an uplink ranging measurementfeedback packet. The PPDU 1132 includes the recorded times t₂ and t₃. Insome embodiments, the PPDU 1132 respectively includes the recordedangles AoA₁ and AoD₂. In some embodiments, the PPDU 1132 optionally alsoincludes respective channel estimate information determined by the AP114 based on reception of the UL NDP 1120.

After receipt of the PPDU 1132, the client station 154 calculates atime-of-flight between the AP 114 and the client station 154 using therecorded times t₁, t₂, t₃, and t₄, according to an embodiment. Anysuitable technique, including currently known techniques, may beutilized to calculate a time-of-flight using the recorded times t₁, t₂,t₃, and t₄. A distance between the AP 114 and the client station 154 maybe calculated using the calculated times-of-flight, e.g., byrespectively multiplying the times-of-flight by the speed of light,according to an embodiment.

In some embodiments, the client station 154 calculates an estimatedposition of the client station using the calculated time-of-flight. Forexample, the client station 154 uses triangulation techniques tocalculate an estimated position of the client station 154 using thecalculated time-of-flight. In some embodiments, the client station 154calculates an estimated positions of the client station also using therecorded angles AoD₁, AoA₁, AoD₂, and AoA₂. For example, the recordedangles AoD₁, AoA₁, AoD₂, and AoA₂ are used as part of a triangulationalgorithm for determining positions of communication devices.

Responsive to receipt of the PPDU 1132, the client station 154 generatesan UL PPDU 1136 that includes an ACK frame, according to an embodiment.The client station 154 transmits the UL PPDU 1136 a defined time periodafter an end of the DL PPDU 1132. In an embodiment, the defined timeperiod is SIFS. In other embodiments, another suitable time period isutilized.

In some embodiments, the DL feedback PPDU 1132 is in a single TXOP withthe UL NDP transmission portion 1104 and the DL NDP transmission portion1108, but includes feedback information for another SU rangingmeasurement exchange (not shown) that occurred prior to the UL NDPtransmission portion 1104 and the DL NDP transmission portion 1108.

As will be described in more detail below, the client station 154 doesnot generate and transmit the UL PPDU 1136 even when the client station154 successfully receives the DL PPDU 1132, according to an embodiment.Thus, in some embodiments, the UL PPDU 1136 is omitted from theprocedure 1100. For example, if the network interface device 162determines (e.g., the MAC processor 166 determines) that the networkinterface device 162 did not successfully receive the DL FB in the PPDU1132, the network interface device 162 determines (e.g., the MACprocessor 166 determines) that the SU ranging measurement exchange 1110is to be repeated.

As discussed above, the DL FB in the PPDU 1132 may include, in additionto recorded times t₂ and t₃, one or more of i) the recorded angles AoA₁,ii) the recorded angles AoD₂, and iii) channel estimate informationdetermined by the AP 114 based on reception of the UL NDP 1120.

In some embodiments, the AP 114 (e.g., the MAC processor 126) determineswhich feedback information is to be included in the PPDU 1132 (e.g., oneor more of i) recorded angle AoA₁, ii) recorded angle AoD₂, and iii)channel estimate information determined by the AP 114 based on receptionof the UL NDP 1120. In some embodiments, the AP 114 (e.g., the MACprocessor 126) determines the granularity of channel estimateinformation to be included in the DL FB PPDU 1132.

In some embodiments, the client station 154 (e.g., the MAC processor166) determines which information (e.g., the recorded angle AoA₁, therecorded angle AoD₂, channel estimate information, channel estimateinformation at a particular granularity, etc.) the AP 114 should includewithin the DL FB PPDU 1132. In some embodiments, the client station 154includes an indication(s) of the requested information in the UL NDPA inthe PPDU 1116. Upon receiving the UL NDPA in the PPDU 1116, the AP 114determines which information to include in the DL FB PPDU 1132.

In some embodiments, the client station 154 (e.g., the MAC processor166) generates one or more MAC frames that include informationconfigured to cause the AP 114 to include, in the DL FB PPDU 1132, therequested information. The client station 154 then transmits the one ormore MAC frames prior to the SU ranging measurement exchange 1100. Uponreceiving the one or more MAC frames prior to the SU ranging measurementexchange 1100, the AP 114 determines which information to include in theDL FB PPDU 1132.

In an embodiment in which the client station 154 informs the AP 114 ofwhich information to include in the DL FB 1132, the client station 154estimates (e.g., the MAC processor 166 estimates) a time required forthe AP 114 to transmit the DL FB PPDU 1132, and the client station 154determines (e.g., the MAC processor 166 determines) a duration of a TXOPin which the SU ranging measurement exchange 1100 is to occur. In anembodiment, the UL NDPA in the PPDU 1116 includes an indication of theduration of the TXOP.

In some embodiments, the AP 114 and the client station 154 negotiatewhether the AP 114 is to include, in the DL FB PPDU 1132, one or more ofi) the recorded angle AoA₁, ii) the recorded angle AoD₂, iii) channelestimate information, and/or iv) the granularity of the channel estimateinformation prior to the SU ranging measurement exchange 1100. Forexample, in an embodiment, negotiating includes the client station 154(e.g., the MAC processor 166) generating one or more MAC frames withinformation indicating requested types of information to be includedand/or requested granularities, and the client station 154 transmits theone or more MAC frames to the AP 114 prior to the SU ranging measurementexchange 1100. Similarly, in an embodiment, negotiating includes the AP114 (e.g., the MAC processor 126) generating one or more MAC frames withinformation indicating proposed types of information to be includedand/or requested granularities, and the AP 114 transmits the one or moreMAC frames to the client station 154 prior to the SU ranging measurementexchange 1100.

FIG. 12 is a diagram of another example SU ranging measurement exchange1200 in another SU ranging measurement procedure, according to anembodiment. The diagram 1200 is described in the context of the examplenetwork 110 merely for explanatory purposes. In some embodiments,signals illustrated in FIG. 12 are generated by other suitablecommunication devices in other suitable types of wireless networks.

The SU ranging measurement exchange 1200 corresponds to a clientstation-initiated SU ranging measurement exchange, according to anembodiment. The SU ranging measurement exchange 1200 is similar to theSU ranging measurement exchange 1100 of FIG. 11A, but a DL FB portion1204 does not begin SIFS after the DL NDP 1128 as in the SU rangingmeasurement exchange 1100 of FIG. 11A. In an embodiment, the UL NDPportion 1104 and the DL NDP portion 1108 occur within a first TXOP 1208,whereas the DL FB portion 1204 occurs within a second TXOP 1212.

In some embodiments, the client station 154 does not transmit the UL ACKPPDU 1136 even when the client station 154 successfully receives the DLFB PPDU 1132, according to an embodiment. Thus, in some embodiments, theUL ACK PPDU 1136 is omitted from the procedure 1200.

In an embodiment, the network interface device 122 determines (e.g., theMAC processor 126 determines) a start time of the second TXOP 1212 suchthat the network interface device 122 will have sufficient time toprepare the feedback information to be included in the DL FB PPDU 1132.In an embodiment, the network interface device 122 determines (e.g., theMAC processor 126 determines) an earliest transmission time of the DL FBPPDU 1132 during the second TXOP 1212 such that the network interfacedevice 122 will have sufficient time to prepare the feedback informationto be included in the DL FB PPDU 1132.

In an embodiment, the network interface device 122 determines (e.g., theMAC processor 126 determines) a delay period after the DL NDP 1128 suchthat the AP 114 will have sufficient time to prepare the feedbackinformation to be included in the DL FB PPDU 1132. The AP 114 thendetermines (e.g., the MAC processor 126 determines) when to initiatetransmission of the DL FB PPDU 1132 based on the determined delayperiod.

Referring again to FIG. 11A, the UL NDP portion 1104, the DL NDP portion1108, and the DL FB portion 1112 are performed during a single TXOP, buta delay between the DL NDP portion 1108 and the DL FB PPDU 1132 isprovided so that the network interface device 122 has more time toprepare feedback information to be included in the DL FB PPDU 1132,according to an embodiment.

In an embodiment, the AP 114 reports (e.g., transmits to the clientstation 154) a time required by the AP 114 to prepare the feedbackinformation to be included in the DL FB PPDU 1132, and the clientstation 154 (e.g., the MAC processor 166) uses the reported time todetermine an earliest start time of the second TXOP 1212 such thatclient station 154 can i) go into a power save mode until the earlieststart time of the second TXOP, ii) perform a frame exchange with anothercommunication device prior to the second TXOP 1212, etc. In anembodiment, the network interface device 162 determines (e.g., the MACprocessor 166 determines) an earliest transmission time of the DL FBPPDU 1132, and the client station 154 (e.g., the MAC processor 166) usesthe reported time to determine an earliest start time of thetransmission time of the DL FB PPDU 1132 such that client station 154can i) go into a power save mode until the transmission time of the DLFB PPDU 1132, ii) perform a frame exchange with another communicationdevice prior to transmission of the DL FB PPDU 1132, etc.

In an embodiment, the AP 114 reports (e.g., transmits to the clientstation 154) a time required by the AP 114 to prepare the feedbackinformation to be included in the DL FB PPDU 1132 in a capabilitiesinformation element included in a MAC frame such as a beacon frame, anassociation response frame, a reassociation response frame, etc. In anembodiment, the capabilities information element includes a field forreporting a time required by a station to prepare the feedbackinformation to be included in a PPDU related to DL ranging measurementfeedback.

In an embodiment, if the client station 154 does not successfullyreceive the DL NDP 1128, the network interface device 162 determines(e.g., the MAC processor 166 determines) that the SU ranging measurementexchange 1200 is to be restarted. Thus, in an embodiment, after theclient station 154 receives the DL FB PPDU 1132, the client stationtransmits a new PPDU with a new UL NDPA similar to the UL NDPA 1116 anda new UL NDP similar to the UL NDP 1120 to restart the SU rangingmeasurement exchange 1200. In an embodiment, the network interface 162(e.g., the MAC processor 166) generates the new UL NDPA with a sequencenumber that is the same as a sequence number included in the original ULNDPA of the PPDU 1116. When the AP 114 receives the new PPDU thatincludes the new UL NDPA with the same sequence number as in theoriginal UL NDPA of the PPDU 1116, the AP 114 determines (e.g., the MACprocessor 126 determines) that i) any measurements taken with regard tothe original UL NDP 1120 should be discarded, and ii) the measurementsshould be retaken in connection with the new UL NDP, according to anembodiment.

In some embodiments in which the client station 154 does not transmit ULACK PPDUs 1136, if the client station 154 does not successfully receivethe DL FB PPDU 1132, the network interface device 162 determines (e.g.,the MAC processor 166 determines) that the SU ranging measurementexchange 1200 is to be restarted. Thus, in an embodiment, in response todetermining that the DL FB PPDU 1132 was not successfully received, theclient station transmits a new PPDU with a new UL NDPA similar to the ULNDPA 1116 and a new UL NDP similar to the UL NDP 1120 to restart the SUranging measurement exchange 1200. In an embodiment, the networkinterface 162 (e.g., the MAC processor 166) generates the new UL NDPAwith a sequence number that is the same as a sequence number included inthe original UL NDPA of the PPDU 1116. When the AP 114 receives the newPPDU that includes the new UL NDPA with the same sequence number as inthe original UL NDPA of the PPDU 1116, the AP 114 determines (e.g., theMAC processor 126 determines) that i) any measurements taken with regardto the original UL NDP 1120 should be discarded, and ii) themeasurements should be retaken in connection with the new UL NDP,according to an embodiment.

FIG. 13 is a diagram of another example SU ranging measurement exchange1300 in another SU ranging measurement procedure, according to anembodiment. The diagram 1300 is described in the context of the examplenetwork 110 merely for explanatory purposes. In some embodiments,signals illustrated in FIG. 13 are generated by other suitablecommunication devices in other suitable types of wireless networks.

The SU ranging measurement exchange 1300 corresponds to a clientstation-initiated SU ranging measurement exchange, according to anembodiment. The SU ranging measurement exchange 1300 is similar to theSU ranging measurement exchange 1100 of FIG. 11A, but a DL FB portion1304 is different than the DL FB portion 1112 of FIG. 11A. In anembodiment, the UL NDP portion 1104, the DL NDP portion 1108, and the DLFB portion 1304 occur within a single TXOP.

In an embodiment, the network device 162 generates (e.g., the MACprocessor 166 generates) an UL FB poll frame, and the network device 162transmits (e.g., the PHY processor 170 transmits) the UL FB poll framein a PPDU 1308. The UL FB poll frame is configured to cause the AP 114to transmit DL FB that includes the recorded times t₂ and t₃. In someembodiments, the DL FB includes the recorded angles AoA₁ and AoD₂. Insome embodiments, the DL FB optionally also includes channel estimateinformation determined by the AP 114 based on reception of the UL NDP1120.

In an embodiment, the UL FB poll frame is a MAC frame configured tocause the AP 114 to transmit the DL FB. In an embodiment, each of the ULNDPA frame in the PPDU 1116 and the UL FB poll frame in the PPDU 1308 isan NDPA frame that includes a field that indicates whether the NDPAframe is i) initiating a SU NDP ranging measurement exchange, or ii) issoliciting feedback in connection with the SU NDP ranging measurementexchange.

In an embodiment, the client station 154 conditionally transmits the ULFB poll frame in a PPDU 1308 based on whether the client station 154successfully received the DL NDP 1128. For example, the networkinterface device 162 determines (e.g., the MAC processor 166 determines)whether the network interface device 162 successfully received the DLNDP 1128. In response to determining that the network interface device162 successfully received the DL NDP 1128, the network interface device162 transmits the UL FB poll frame in a PPDU 1308. On the other hand, inresponse to determining that the network interface device 162 did notsuccessfully receive the DL NDP 1128, the network interface device 162does not transmit the UL FB poll frame in a PPDU 1308; rather, thenetwork interface device 162 restarts the SU ranging measurementexchange 1300 by transmitting an UL NDPA in a PPDU 1116.

In an embodiment, the AP 114 transmits a DL PPDU 1312 a defined timeperiod after an end of the UL PPDU 1308. In an embodiment, the definedtime period is SIFS. In other embodiments, another suitable time periodis utilized. In some embodiments, the client station 154 transmits anACK frame (not shown) in response to successfully receiving the DL FB inthe DL PPDU 1312. In other embodiments, the client station 154 does nottransmits an ACK frame even when the client station 154 successfullyreceives the DL FB in the DL PPDU 1312.

FIG. 14 is a diagram of another example SU ranging measurement exchange1400 in another SU ranging measurement procedure, according to anembodiment. The diagram 1400 is described in the context of the examplenetwork 110 merely for explanatory purposes. In some embodiments,signals illustrated in FIG. 14 are generated by other suitablecommunication devices in other suitable types of wireless networks.

The SU ranging measurement exchange 1400 corresponds to a clientstation-initiated SU ranging measurement exchange, according to anembodiment. The SU ranging measurement exchange 1400 is similar to theSU ranging measurement exchange 1300 of FIG. 13, but a DL FB portion1404 does not begin SIFS after the DL NDP 1128 as in the SU rangingmeasurement exchange 1300 of FIG. 13. In an embodiment, the UL NDPportion 1104 and the DL NDP portion 1108 occur within a first TXOP 1408,whereas the DL FB portion 1404 occurs within a second TXOP 1412.

In an embodiment, the network interface device 162 determines (e.g., theMAC processor 166 determines) a start time of the second TXOP 1412 suchthat the AP 114 will have sufficient time to prepare the feedbackinformation to be included in the DL FB PPDU 1312. In an embodiment, thenetwork interface device 162 determines (e.g., the MAC processor 126determines) an earliest transmission time of the UL FB Poll PPDU 1308during the second TXOP 1412 such that the AP 114 will have sufficienttime to prepare the feedback information to be included in the DL FBPPDU 1312.

In an embodiment, the network interface device 162 determines (e.g., theMAC processor 166 determines) a delay period after the DL NDP 1128 suchthat the AP 114 will have sufficient time to prepare the feedbackinformation to be included in the DL FB PPDU 1312. The client stationthen determines (e.g., the MAC processor 166 determines) when toinitiate transmission of the UL FB Poll PPDU 1308 based on thedetermined delay period.

Referring again to FIG. 13, the UL NDP portion 1104, the DL NDP portion1108, and the DL FB portion 1304 are performed during a single TXOP, buta delay between the DL NDP portion 1108 and the UL FB poll PPDU 1308 isprovided so that the AP 114 has more time to prepare feedbackinformation to be included in the DL FB PPDU 1312, according to anembodiment.

In an embodiment, the AP 114 reports (e.g., transmits to the clientstation 154) a time required by the AP 114 to prepare the feedbackinformation to be included in the DL FB PPDU 1312, and the clientstation 154 (e.g., the MAC processor 166) uses the reported time todetermine an earliest start time of the second TXOP 1412 such thatclient station 154 can i) go into a power save mode until the earlieststart time of the second TXOP 1412, ii) perform a frame exchange withanother communication device prior to the second TXOP 1412, etc. In anembodiment, the network interface device 162 determines (e.g., the MACprocessor 166 determines) an earliest transmission time of the UL FBPoll PPDU 1308 such that client station 154 can i) go into a power savemode until the transmission time of the UL FB Poll PPDU 1308, ii)perform a frame exchange with another communication device prior totransmission of the UL FB Poll PPDU 1308, etc.

In an embodiment, the AP 114 reports (e.g., transmits to the clientstation 154) a time required by the AP 114 to prepare the feedbackinformation to be included in the DL FB PPDU 1312 in a capabilitiesinformation element included in a MAC frame such as a beacon frame, anassociation response frame, a reassociation response frame, etc. In anembodiment, the capabilities information element includes a field forreporting a time required by a station to prepare the feedbackinformation to be included in a PPDU related to DL ranging measurementfeedback.

In an embodiment, if the client station 154 does not successfullyreceive the DL NDP 1128, the network interface device 162 determines(e.g., the MAC processor 166 determines) that the SU ranging measurementexchange 1200 is to be restarted. Thus, in an embodiment, in response tothe network interface device 162 determining (e.g., the MAC processor166 determining), that the network interface device 162 did notsuccessfully receive the DL NDP 1128, the client station transmits a newPPDU with a new UL NDPA similar to the UL NDPA 1116 and a new UL NDPsimilar to the UL NDP 1120 to restart the SU ranging measurementexchange 1400. In an embodiment, the network interface 162 (e.g., theMAC processor 166) generates the new UL NDPA with a sequence number thatis the same as a sequence number included in the original UL NDPA of thePPDU 1116. When the AP 114 receives the new PPDU that includes the newUL NDPA with the same sequence number as in the original UL NDPA of thePPDU 1116, the AP 114 determines (e.g., the MAC processor 126determines) that i) any measurements taken with regard to the originalUL NDP 1120 should be discarded, and ii) the measurements should beretaken in connection with the new UL NDP, according to an embodiment.

In some embodiments in which the client station 154 does not transmit ULACK PPDUs in response to successfully receiving the DL FB PPDU 1312, ifthe client station 154 does not successfully receive the DL FB PPDU1312, the network interface device 162 determines (e.g., the MACprocessor 166 determines) that another UL FB poll PPDU similar to the ULFB poll PPDU 1308 is to be transmitted. Thus, in an embodiment, inresponse to determining that the DL FB PPDU 1312 was not successfullyreceived, the client station transmits a new UL FB poll PPDU similar tothe UL FB poll PPDU 1308.

Although FIGS. 11A, 11B, and 12-14 were described in the context of aranging measurement exchange between a client station and an AP, inother embodiments, the same or similar ranging measurement exchanges areperformed between two client stations.

FIG. 15 is a flow diagram of an example method 1500 for performing aranging measurement exchange, according to an embodiment. In someembodiments, the network interface device 162 of FIG. 1 is configured toimplement the method 1500. The method 1500 is described in the contextof the network interface device 162 merely for explanatory purposes and,in other embodiments, the method 1500 is implemented by another suitablecommunication device. The method 1500 can be implemented in the contextof ranging measurement exchanges such as those described with referenceto FIGS. 11A and 12-14, according to some embodiments. The method 1500,however, is implemented in connection with other suitable rangingexchanges, in other embodiments.

At block 1504, a first communication device determines (e.g., thenetwork interface device 162 determines, e.g., the MAC processor 126 ofthe network interface device 122 determines; etc.) information that asecond communication device (e.g., the AP 114, another client station,etc.) is to provide in a feedback transmission (e.g., the DL FB PPDU1132, the DL FB PPDU 1312, etc.) to the first communication device,wherein the feedback transmission is a part of the ranging measurementexchange. In an embodiment, the MAC processor 166 determines whether thesecond communication device is to include, in the feedback transmission,one or more of i) the recorded angle AoA₁, ii) the recorded angle AoD₂,iii) channel estimate information, and/or iv) the granularity of thechannel estimate information.

In some embodiments, block 1504 comprises the first communication devicedetermining the information that the second communication device is toprovide in the feedback transmission without negotiating with the secondcommunication device regarding which information (and/or, if theinformation includes channel estimate information, a granularity of thechannel estimate information) the second communication device is toprovide in the feedback transmission. In other embodiments, block 1504comprises the first communication device negotiating with the secondcommunication device regarding which information (and/or, if theinformation includes channel estimate information, a granularity of thechannel estimate information) the second communication device is toprovide in the uplink feedback transmission.

At block 1508, the first communication device transmits (e.g., thenetwork interface device 162 transmits, etc.) to the secondcommunication device an indication or indications of the informationdetermined at block 1504. In an embodiment, the network interface device162 includes an indication or indications of the information determinedat block 1504 in the UL NDPA PPDU 1116 216 (FIGS. 11A, 12-14). In anembodiment, the network interface device 162 includes an indication orindications of the information determined at block 1504 in the UL FPpoll PPDU 1308 (FIGS. 13, 14). In an embodiment, the network interfacedevice 162 includes an indication or indications of the informationdetermined at block 1504 in a PPDU transmitted prior to the rangingmeasurement exchange 1100/1200/1300/1400.

At block 1512, the first communication device performs the rangingmeasurement exchange with the second communication device. Block 1512includes the first communication device receiving, in a feedbacktransmission from the second communication device, wherein the feedbacktransmission includes the information determined at block 404. In anembodiment, block 1512 includes performing the uplink transmissionsdiscussed with respect to any of FIGS. 11A and 12-14, and receiving thedownlink transmissions discussed with respect to any of FIGS. 11A and12-14. In an embodiment, block 1512 includes receiving the informationdetermined at block 1504 in DL FB PPDU 1132 or DL FB PPDU 1312.

FIG. 16 is a flow diagram of another example method 1600 for performinga ranging measurement exchange, according to an embodiment. In someembodiments, the network interface device 122 of FIG. 1 is configured toimplement the method 1600. The method 1600 is described in the contextof the network interface device 122 merely for explanatory purposes and,in other embodiments, the method 1600 is implemented by another suitablecommunication device, such as the network interface device 162. Themethod 1600 can be implemented in the context of ranging measurementexchanges such as those described with reference to FIGS. 11A and 12-14,according to some embodiments. The method 1600, however, is implementedin connection with other suitable ranging exchanges, in otherembodiments.

At block 1604, a first communication device determines (e.g., thenetwork interface device 122 determines, e.g., the MAC processor 126 ofthe network interface device 122 determines; etc.) information that thefirst communication device is to provide in a feedback transmission(e.g., the DL FB PPDU 1132/1312) to a second communication device (e.g.,the client station 154), wherein the feedback transmission is a part ofthe ranging measurement exchange. In an embodiment, the MAC processor126 determines whether the DL FB PPDU 1132/1312 is to include one ormore of i) the recorded angle AoA₁, ii) the recorded angle AoD₂, iii)channel estimate information, and/or iv) the granularity of the channelestimate information.

In some embodiments, block 1604 comprises the first communication devicedetermining the information that is to be provided in the feedbacktransmission without being instructed by, and without negotiating with,the second communication device regarding which information (and/or, ifthe information includes channel estimate information, a granularity ofthe channel estimate information) is to be provided in the feedbacktransmission.

In another embodiment, the method 1600 is performed in conjunction withthe method 1500, and block 1604 comprises receiving a transmission fromthe second communication device (e.g., corresponding to the transmissionof block 1508 of FIG. 15), where the transmission includes anindication(s) of which information (and/or, if the information includeschannel estimate information, a granularity of the channel estimateinformation) is to be provided in the feedback transmission. In variousembodiments, the received transmission is the NDPA PPDU 116, the UL FBpoll PPDU 1308, or a transmission prior to the ranging measurementexchange. In another embodiment, the method 1600 is performed inconjunction with the method 1500, and block 1604 comprises negotiatingwith the second communication device regarding which information(and/or, if the information includes channel estimate information, agranularity of the channel estimate information) is to be provided inthe feedback transmission.

At block 1608, the first communication device performs the rangingmeasurement exchange with the second communication device. Block 1608includes the first communication device transmitting, in a feedbacktransmission, the information determined at block 1604. In anembodiment, block 1608 includes performing the downlink transmissionsdiscussed with respect to any of FIGS. 11A and 12-14, and receiving theuplink transmissions discussed with respect to any of FIGS. 11A and12-14. In an embodiment, block 1608 includes transmitting theinformation determined at block 1604 in DL FB PPDU 1132 or DL FB PPDU1312.

FIG. 17 is a flow diagram of an example method 1700 for performing aranging measurement exchange, according to an embodiment. In someembodiments, the network interface device 122 of FIG. 1 is configured toimplement the method 1700. In other embodiments, the network interfacedevice 162 of FIG. 1 is configured to implement the method 1700. Themethod 1700 is described in the context of the network interface device122/162 merely for explanatory purposes and, in other embodiments, themethod 1700 is implemented by another suitable communication device. Themethod 1700 can be implemented in the context of ranging measurementexchanges such as those described with reference to FIGS. 11A and 12-14,according to some embodiments. The method 1700, however, is implementedin connection with other suitable ranging exchanges, in otherembodiments.

At block 1704, a first communication device determines (e.g., thenetwork interface device 122 determines, e.g., the MAC processor 126 ofthe network interface device 122 determines; the network interfacedevice 162 determines, e.g., the MAC processor 166 of the networkinterface device 162 determines; etc.) a delay period associated with acommunication device (e.g., the first communication device or a secondcommunication device) generating feedback information as part of aranging measurement exchange. For example, with regard to DL feedback,the AP 114 reports a time required by the AP 114 to prepare feedbackinformation to be included in the DL FB PPDU 1132/1312 in a capabilitiesinformation element included in a MAC frame such as a beacon frame, anassociation response frame, a reassociation response frame, etc.,according to an embodiment, and the MAC processor 166 of the networkinterface device 162 determines the delay period based on the reportedtime. As another example, with regard to DL feedback, the MAC processor126 retrieves a predetermined delay period from a memory device,according to an embodiment. As another example, with regard to feedbackfrom another client station, the other client station reports a timerequired by the other client station to prepare feedback information tobe included in a FB PPDU like the PPDU 1132/1312 in a capabilitiesinformation element included in a MAC frame such as an associationrequest frame, a reassociation request frame, etc., according to anembodiment, and the MAC processor 166 of the network interface device162 determines the delay period based on the reported time.

At block 1708, the first communication device uses (e.g., the networkinterface device 122 uses, e.g., the MAC processor 126 of the networkinterface device 122 uses; the network interface device 162 uses, e.g.,the MAC processor 166 of the network interface device 122 uses; etc.)the determined delay period to determine when to initiate a feedbacktransmission that is part of the ranging measurement exchange.

For example, with respect to the example ranging measurement exchange1100 of FIG. 11A, the first communication device determines (e.g., thenetwork interface device 122 determines, e.g., the MAC processor 126 ofthe network interface device 122 determines; etc.) when to initiatetransmission of the DL FB PPDU 1132, according to an embodiment. Asanother example, with respect to the example ranging measurementexchange 1200 of FIG. 12, the first communication device determines(e.g., the network interface device 122 determines, e.g., the MACprocessor 126 of the network interface device 122 determines; etc.) whento initiate the TXOP 1212 and/or initiate transmission of the DL FB PPDU1132, according to an embodiment.

As another example, with respect to the example ranging measurementexchange 1300 of FIG. 13, the first communication device determines(e.g., the network interface device 162 determines, e.g., the MACprocessor 166 of the network interface device 162 determines; etc.) whento initiate transmission of the UL FB poll PPDU 1308, according to anembodiment. As another example, with respect to the example rangingmeasurement exchange 1400 of FIG. 14, the first communication devicedetermines (e.g., the network interface device 162 determines, e.g., theMAC processor 166 of the network interface device 162 determines; etc.)when to initiate the TXOP 1212 and/or transmission of the UL FB pollPPDU 1308, according to an embodiment.

At block 1712, when the first communication device determines that thefeedback transmission is to be initiated, the first communication deviceinitiates (e.g., the network interface device 122 initiates, e.g., theMAC processor 126 of the network interface device 122 initiates; thenetwork interface device 162 initiates, e.g., the MAC processor 166 ofthe network interface device 162 initiates; etc.) the feedbacktransmission.

For example, with respect to the example ranging measurement exchange1100 of FIG. 11A and the example ranging measurement exchange 1200 ofFIG. 12, the first communication device initiates (e.g., the networkinterface device 122 initiates, e.g., the MAC processor 126 of thenetwork interface device 122 initiates; etc.) transmission of the DL FBPPDU 1132, according to an embodiment.

As another example, with respect to the example ranging measurementexchange 1300 of FIG. 13 and the example ranging measurement exchange1400 of FIG. 14, the first communication device initiates (e.g., thenetwork interface device 162 initiates, e.g., the MAC processor 166 ofthe network interface device 162 initiates; etc.) e transmission of theUL FB poll PPDU 1308, according to an embodiment.

Various techniques described in connection with FIGS. 11A and 12-17 canbe used in combination. For example, various techniques described inconnection with FIGS. 15 and 16 can be used in combination with varioustechniques described in connection with FIG. 17.

Embodiment 1

A method, including: determining, at a first communication device, whichone or more types of feedback information, from among a plurality oftypes of feedback information associated with a range measurementexchange session, a second communication device is to provide to thefirst communication device in a feedback packet transmitted as part ofthe range measurement exchange session; transmitting, by the firstcommunication device and to the second communication device, one or moreindications of the determined one or more types of feedback informationthat the second communication device is to provide to the firstcommunication device in the feedback packet; and performing, at thefirst communication device, the range measurement exchange, includingreceiving the feedback packet from the second communication device,wherein the feedback packet includes the determined one or more types offeedback information.

Embodiment 2

The method of embodiment 1, wherein the plurality of types ofinformation includes: an angle of arrival of a first null data packet,an angle of departure of a second null data packet, and channel estimateinformation determined based on reception of the first null data packet.

Embodiment 3

The method of embodiment 2, wherein the plurality of types ofinformation further includes: a first granularity of the channelestimate information, and a second granularity of the channel estimateinformation.

Embodiment 4

The method of any of embodiments 1-3, wherein determining which one ormore types of feedback information the second communication device is toprovide in the feedback packet comprises: exchanging packets between thefirst communication device and the second communication device as partof a negotiation regarding which one or more types of feedbackinformation the second communication device is to provide in thefeedback packet.

Embodiment 5

The method of any of embodiments 1-3, wherein: performing the rangemeasurement exchange comprises transmitting i) a null data packetannouncement (NDPA) frame, and ii) transmitting a null data packet(NDP); and transmitting the one or more indications of the determinedone or more types of feedback information includes transmitting the oneor more indications of the determined one or more types of feedbackinformation in the NDPA.

Embodiment 6

The method of any of embodiments 1-3, wherein: the range measurementexchange is a multi-user range measurement exchange; the secondcommunication device is a client station among a plurality of clientstations participating in the multi-user range measurement exchange;performing the range measurement exchange comprises transmitting atrigger frame to cause the plurality of client stations to transmitrange measurement feedback information as part of an uplink multi-usertransmission; the feedback packet is included in the multi-usertransmission; and transmitting the one or more indications of thedetermined one or more types of feedback information includestransmitting the one or more indications of the determined one or moretypes of feedback information in the trigger frame.

Embodiment 7

The method of embodiment 6, further comprising: determining, at thefirst communication device, a delay time to permit the plurality ofclient stations to prepare the range measurement feedback information;and determining, at the first communication device, when to transmit thetrigger frame based on the delay time.

Embodiment 8

The method of any of embodiments 1-3, wherein: performing the rangemeasurement exchange comprises transmitting a poll frame to cause thesecond communication device to transmit the feedback packet; andtransmitting the one or more indications of the determined one or moretypes of feedback information includes transmitting the one or moreindications of the determined one or more types of feedback informationin the poll frame.

Embodiment 9

The method of embodiment 8, further comprising: determining, at thefirst communication device, a delay time to permit the secondcommunication device to prepare the feedback information; anddetermining, at the first communication device, when to transmit thepoll frame based on the delay time.

Embodiment 10

The method of any of embodiments 1-9, further comprising: determining,at the first communication device, that the feedback packet wassuccessfully received; and not transmitting, by the first communicationdevice, an acknowledgment packet to acknowledge successfully receivingthe feedback packet.

Embodiment 11

An apparatus, comprising: a network interface device associated with afirst communication device. The network interface device is configuredto: determine which one or more types of feedback information, fromamong a plurality of types of feedback information associated with arange measurement exchange session, a second communication device is toprovide to the first communication device in a feedback packettransmitted as part of the range measurement exchange session; andtransmit, to the second communication device, one or more indications ofthe determined one or more types of feedback information that the secondcommunication device is to provide to the first communication device inthe feedback packet, and perform the range measurement exchange,including receiving the feedback packet from the second communicationdevice, wherein the feedback packet includes the determined one or moretypes of feedback information.

Embodiment 12

The apparatus of embodiment 11, wherein the plurality of types ofinformation includes: an angle of arrival of a first null data packet,an angle of departure of a second null data packet, and channel estimateinformation determined based on reception of the first null data packet.

Embodiment 13

The apparatus of embodiment 12, wherein the plurality of types ofinformation further includes: a first granularity of the channelestimate information, and a second granularity of the channel estimateinformation.

Embodiment 14

The apparatus of any of embodiments 11-13, wherein the network interfacedevice is configured to: exchange packets between the firstcommunication device and the second communication device as part of anegotiation regarding which one or more types of feedback informationthe second communication device is to provide in the feedback packet.

Embodiment 15

The apparatus of any of embodiments 11-13, wherein the network interfacedevice is configured to: transmit i) a null data packet announcement(NDPA) frame, and ii) transmitting a null data packet (NDP) as part ofperforming the range measurement exchange; and transmit the one or moreindications of the determined one or more types of feedback informationin the NDPA.

Embodiment 16

The apparatus of any of embodiments 11-13, wherein: the rangemeasurement exchange is a multi-user range measurement exchange; thesecond communication device is a client station among a plurality ofclient stations participating in the multi-user range measurementexchange; the network interface device is configured to transmit atrigger frame, as part of performing the range measurement exchange, tocause the plurality of client stations to transmit range measurementfeedback information as part of an uplink multi-user transmission; thefeedback packet is included in the multi-user transmission; and thenetwork interface device is configured to transmit the one or moreindications of the determined one or more types of feedback informationin the trigger frame.

Embodiment 17

The apparatus of embodiments 16, wherein the network interface device isconfigured to: determine a delay time to permit the plurality of clientstations to prepare the range measurement feedback information; anddetermine when to transmit the trigger frame based on the delay time.

Embodiment 18

The apparatus of any of embodiments 11-13, wherein the network interfacedevice is configured to: transmit a poll frame, as part of performingthe range measurement exchange, to cause the second communication deviceto transmit the feedback packet; and transmit the one or moreindications of the determined one or more types of feedback informationin the poll frame.

Embodiment 19

The apparatus of embodiments 18, wherein the network interface device isconfigured to: determine a delay time to permit the second communicationdevice to prepare the feedback information; and determine when totransmit the poll frame based on the delay time.

Embodiment 20

The apparatus of any of embodiments 11-13, wherein the network interfacedevice is configured to: determine that the feedback packet wassuccessfully received; and not transmit an acknowledgment packet toacknowledge successfully receiving the feedback packet.

Embodiment 21

A method, including: determining, at a first communication device, whichone or more types of feedback information, from among a plurality oftypes of feedback information associated with a range measurementexchange session, the first communication device is to provide to asecond communication device in a feedback packet transmitted as part ofthe range measurement exchange session; and performing, at the firstcommunication device, the range measurement exchange with the secondcommunication device, including transmitting the feedback packet to thesecond communication device, wherein the feedback packet includes thedetermined one or more types of feedback information.

Embodiment 22

The method of embodiment 21, wherein the plurality of types ofinformation includes: an angle of arrival of a first null data packet,an angle of departure of a second null data packet, and channel estimateinformation determined based on reception of the first null data packet.

Embodiment 23

The method of embodiment 22, wherein the plurality of types ofinformation further includes: a first granularity of the channelestimate information, and a second granularity of the channel estimateinformation.

Embodiment 24

The method of any of embodiments 21-23, wherein determining which one ormore types of feedback information the first communication device is toprovide in the feedback packet comprises: exchanging packets between thefirst communication device and the second communication device as partof a negotiation regarding which one or more types of feedbackinformation the first communication device is to provide in the feedbackpacket.

Embodiment 25

The method of any of embodiments 21-23, wherein: performing the rangemeasurement exchange comprises receiving, at the first communicationdevice, i) a null data packet announcement (NDPA) frame from the secondcommunication device, and ii) a null data packet (NDP) from the secondcommunication device; and determining which one or more types offeedback information the first communication device is to provide to thesecond communication device includes analyzing, in the NDPA, one or moreindications of which one or more types of feedback information the firstcommunication device is to provide to the second communication device.

Embodiment 26

The method of any of embodiments 21-23, wherein: the range measurementexchange is a multi-user range measurement exchange; the firstcommunication device is a client station among a plurality of clientstations participating in the multi-user range measurement exchange; thesecond communication device is an access point (AP); performing therange measurement exchange comprises receiving a trigger frame from theAP, the trigger frame configured to cause the plurality of clientstations to transmit range measurement feedback information as part ofan uplink multi-user transmission; the feedback packet is transmitted inresponse to the trigger frame; and determining which one or more typesof feedback information the first communication device is to provide tothe second communication device includes analyzing, in the triggerframe, one or more indications of which one or more types of feedbackinformation the first communication device is to provide to the secondcommunication device.

Embodiment 27

The method of any of embodiments 21-23, wherein: performing the rangemeasurement exchange comprises receiving a poll frame to configured tocause the first communication device to transmit the feedback packet;and determining which one or more types of feedback information thefirst communication device is to provide to the second communicationdevice includes analyzing, in the poll frame, one or more indications ofwhich one or more types of feedback information the first communicationdevice is to provide to the second communication device.

Embodiment 28

An apparatus, comprising: a network interface device. The networkinterface device is configured to: determine which one or more types offeedback information, from among a plurality of types of feedbackinformation associated with a range measurement exchange session, is tobe provided to a second communication device in a feedback packettransmitted as part of the range measurement exchange session; andperform the range measurement exchange, including transmitting thefeedback packet to the second communication device, wherein the feedbackpacket includes the determined one or more types of feedbackinformation.

Embodiment 29

The apparatus of embodiment 28, wherein the plurality of types ofinformation includes: an angle of arrival of a first null data packet,an angle of departure of a second null data packet, and channel estimateinformation determined based on reception of the first null data packet.

Embodiment 30

The apparatus of embodiment 29, wherein the plurality of types ofinformation further includes: a first granularity of the channelestimate information, and a second granularity of the channel estimateinformation.

Embodiment 31

The apparatus of any of embodiments 28-30, wherein the network interfacedevice is configured to: exchange packets between the firstcommunication device and the second communication device as part of anegotiation regarding which one or more types of feedback informationthe first communication device is to provide in the feedback packet.

Embodiment 32

The apparatus of any of embodiments 28-30, wherein the network interfacedevice is configured to: receive, as part of the range measurementexchange, i) a null data packet announcement (NDPA) frame from thesecond communication device, and ii) a null data packet (NDP) from thesecond communication device; and analyze, in the NDPA, one or moreindications of which one or more types of feedback information the firstcommunication device is to provide to the second communication device.

Embodiment 33

The apparatus of any of embodiments 28-30, wherein: the rangemeasurement exchange is a multi-user range measurement exchange; thefirst communication device is a client station among a plurality ofclient stations participating in the multi-user range measurementexchange; the second communication device is an access point (AP); thenetwork interface device is configured to receive, as part of the rangemeasurement exchange, a trigger frame from the AP, the trigger frameconfigured to cause the plurality of client stations to transmit rangemeasurement feedback information as part of an uplink multi-usertransmission; the feedback packet is transmitted in response to thetrigger frame; and the network interface device is configured toanalyze, in the trigger frame, one or more indications of which one ormore types of feedback information the first communication device is toprovide to the second communication device.

Embodiment 34

The apparatus of any of embodiments 28-30, wherein the network interfacedevice is configured to: receive, as part of the range measurementexchange, a poll frame to configured to cause the first communicationdevice to transmit the feedback packet; and analyze one or moreindications, in the poll frame, of which one or more types of feedbackinformation the first communication device is to provide to the secondcommunication device.

At least some of the various blocks, operations, and techniquesdescribed above may be implemented utilizing hardware, a processorexecuting firmware instructions, a processor executing softwareinstructions, or any combination thereof. When implemented utilizing aprocessor executing software or firmware instructions, the software orfirmware instructions may be stored in any computer readable memory suchas on a magnetic disk, an optical disk, or other storage medium, in aRAM or ROM or flash memory, processor, hard disk drive, optical diskdrive, tape drive, etc. The software or firmware instructions mayinclude machine readable instructions that, when executed by one or moreprocessors, cause the one or more processors to perform various acts.

When implemented in hardware, the hardware may comprise one or more ofdiscrete components, an integrated circuit, an application-specificintegrated circuit (ASIC), a programmable logic device (PLD), etc.

While the present invention has been described with reference tospecific examples, which are intended to be illustrative only and not tobe limiting of the invention, changes, additions and/or deletions may bemade to the disclosed embodiments without departing from the scope ofthe invention.

What is claimed is:
 1. A method, comprising: determining, at a firstcommunication device, which one or more types of feedback information,from among a plurality of types of feedback information associated witha range measurement exchange session, a second communication device isto provide to the first communication device in a feedback packettransmitted as part of the range measurement exchange session;transmitting, by the first communication device and to the secondcommunication device, one or more indications of the determined one ormore types of feedback information that the second communication deviceis to provide to the first communication device in the feedback packet;and performing, at the first communication device, the range measurementexchange, including receiving the feedback packet from the secondcommunication device, wherein the feedback packet includes thedetermined one or more types of feedback information.
 2. The method ofclaim 1, wherein the plurality of types of information includes: anangle of arrival of a first null data packet, an angle of departure of asecond null data packet, and channel estimate information determinedbased on reception of the first null data packet.
 3. The method of claim2, wherein the plurality of types of information further includes: afirst granularity of the channel estimate information, and a secondgranularity of the channel estimate information.
 4. The method of claim1, wherein determining which one or more types of feedback informationthe second communication device is to provide in the feedback packetcomprises: exchanging packets between the first communication device andthe second communication device as part of a negotiation regarding whichone or more types of feedback information the second communicationdevice is to provide in the feedback packet.
 5. The method of claim 1,wherein: performing the range measurement exchange comprisestransmitting i) a null data packet announcement (NDPA) frame, and ii)transmitting a null data packet (NDP); and transmitting the one or moreindications of the determined one or more types of feedback informationincludes transmitting the one or more indications of the determined oneor more types of feedback information in the NDPA.
 6. The method ofclaim 1, wherein: the range measurement exchange is a multi-user rangemeasurement exchange; the second communication device is a clientstation among a plurality of client stations participating in themulti-user range measurement exchange; performing the range measurementexchange comprises transmitting a trigger frame to cause the pluralityof client stations to transmit range measurement feedback information aspart of an uplink multi-user transmission; the feedback packet isincluded in the multi-user transmission; and transmitting the one ormore indications of the determined one or more types of feedbackinformation includes transmitting the one or more indications of thedetermined one or more types of feedback information in the triggerframe.
 7. The method of claim 6, further comprising: determining, at thefirst communication device, a delay time to permit the plurality ofclient stations to prepare the range measurement feedback information;and determining, at the first communication device, when to transmit thetrigger frame based on the delay time.
 8. The method of claim 1,wherein: performing the range measurement exchange comprisestransmitting a poll frame to cause the second communication device totransmit the feedback packet; and transmitting the one or moreindications of the determined one or more types of feedback informationincludes transmitting the one or more indications of the determined oneor more types of feedback information in the poll frame.
 9. The methodof claim 8, further comprising: determining, at the first communicationdevice, a delay time to permit the second communication device toprepare the feedback information; and determining, at the firstcommunication device, when to transmit the poll frame based on the delaytime.
 10. The method of claim 1, further comprising: determining, at thefirst communication device, that the feedback packet was successfullyreceived; and not transmitting, by the first communication device, anacknowledgment packet to acknowledge successfully receiving the feedbackpacket.
 11. An apparatus, comprising: a network interface deviceassociated with a first communication device, wherein the networkinterface device includes: one or more integrated circuits (ICs), amedia access control layer protocol (MAC) processor implemented on theone or more ICs, and a physical layer protocol (PHY) processorimplemented on the one or more ICs; wherein the MAC processor isconfigured to: determine which one or more types of feedbackinformation, from among a plurality of types of feedback informationassociated with a range measurement exchange session, a secondcommunication device is to provide to the first communication device ina feedback packet transmitted as part of the range measurement exchangesession; and wherein the network interface device is configured to:transmit, to the second communication device, one or more indications ofthe determined one or more types of feedback information that the secondcommunication device is to provide to the first communication device inthe feedback packet, and perform the range measurement exchange,including receiving the feedback packet from the second communicationdevice, wherein the feedback packet includes the determined one or moretypes of feedback information.
 12. The apparatus of claim 11, whereinthe plurality of types of information includes: an angle of arrival of afirst null data packet, an angle of departure of a second null datapacket, and channel estimate information determined based on receptionof the first null data packet.
 13. The apparatus of claim 12, whereinthe plurality of types of information further includes: a firstgranularity of the channel estimate information, and a secondgranularity of the channel estimate information.
 14. A method,comprising: determining, at a first communication device, which one ormore types of feedback information, from among a plurality of types offeedback information associated with a range measurement exchangesession, the first communication device is to provide to a secondcommunication device in a feedback packet transmitted as part of therange measurement exchange session; and performing, at the firstcommunication device, the range measurement exchange with the secondcommunication device, including transmitting the feedback packet to thesecond communication device, wherein the feedback packet includes thedetermined one or more types of feedback information.
 15. The method ofclaim 14, wherein the plurality of types of information includes: anangle of arrival of a first null data packet, an angle of departure of asecond null data packet, and channel estimate information determinedbased on reception of the first null data packet.
 16. The method ofclaim 15, wherein the plurality of types of information furtherincludes: a first granularity of the channel estimate information, and asecond granularity of the channel estimate information.
 17. The methodof claim 14, wherein determining which one or more types of feedbackinformation the first communication device is to provide in the feedbackpacket comprises: exchanging packets between the first communicationdevice and the second communication device as part of a negotiationregarding which one or more types of feedback information the firstcommunication device is to provide in the feedback packet.
 18. Themethod of claim 14, wherein: performing the range measurement exchangecomprises receiving, at the first communication device, i) a null datapacket announcement (NDPA) frame from the second communication device,and ii) a null data packet (NDP) from the second communication device;and determining which one or more types of feedback information thefirst communication device is to provide to the second communicationdevice includes analyzing one or more indications, in the NDPA, of whichone or more types of feedback information the first communication deviceis to provide to the second communication device.
 19. The method ofclaim 14, wherein: the range measurement exchange is a multi-user rangemeasurement exchange; the first communication device is a client stationamong a plurality of client stations participating in the multi-userrange measurement exchange; the second communication device is an accesspoint (AP); performing the range measurement exchange comprisesreceiving a trigger frame from the AP, the trigger frame configured tocause the plurality of client stations to transmit range measurementfeedback information as part of an uplink multi-user transmission; thefeedback packet is transmitted in response to the trigger frame; anddetermining which one or more types of feedback information the firstcommunication device is to provide to the second communication deviceincludes analyzing one or more indications, in the trigger frame, ofwhich one or more types of feedback information the first communicationdevice is to provide to the second communication device.
 20. The methodof claim 14, wherein: performing the range measurement exchangecomprises receiving a poll frame to configured to cause the firstcommunication device to transmit the feedback packet; and determiningwhich one or more types of feedback information the first communicationdevice is to provide to the second communication device includesanalyzing one or more indications, in the poll frame, of which one ormore types of feedback information the first communication device is toprovide to the second communication device.
 21. An apparatus,comprising: a network interface device associated with a firstcommunication device, wherein the network interface device includes: oneor more integrated circuits (ICs), a media access control layer protocol(MAC) processor implemented on the one or more ICs, and a physical layerprotocol (PHY) processor implemented on the one or more ICs; wherein theMAC processor is configured to: determine which one or more types offeedback information, from among a plurality of types of feedbackinformation associated with a range measurement exchange session, is tobe provided to a second communication device in a feedback packettransmitted as part of the range measurement exchange session; andwherein the network interface device is configured to: perform the rangemeasurement exchange, including transmitting the feedback packet to thesecond communication device, wherein the feedback packet includes thedetermined one or more types of feedback information.
 22. The apparatusof claim 21, wherein the plurality of types of information includes: anangle of arrival of a first null data packet, an angle of departure of asecond null data packet, and channel estimate information determinedbased on reception of the first null data packet.
 23. The apparatus ofclaim 22, wherein the plurality of types of information furtherincludes: a first granularity of the channel estimate information, and asecond granularity of the channel estimate information.